Lakhmir Singh Manjit Kaur Class 10 Chemistry 1st Chapter “Chemical Reactions and Equations” solution

Lakhmir Singh Manjit Kaur Class 10 Chemistry 1st Chapter “Chemical Reactions and Equations” solution

Lakhmir Singh and Manjit Kaur Chemistry solution: “Chemical Reactions and Equations” Chapter 1. Here you get easy solutions of Lakhmir Singh and Manjit Kaur Chemistry solution Chapter 1 . Here we have given Chapter 1 all solution of Class 10. Its help you to complete your homework.

  • Board – CBSE
  • Text Book – Chemistry
  • Class – 10
  • Chapter – 01

Lakhmir Singh Manjit Kaur Class 10 Chemistry 1st Chapter Solution (First Part)

  • Very short type questions:

1) Why is respiration consider an exothermic process

Ans : In our body energy is required to survive .this energy is produce from food at metabolism system in the body . In food glucose molecule is present . In respiration process oxygen is inhale in body and this oxygen and glucose molecule is combined with each other and oxidation of glucose molecule is taking place to form carbon monoxide and water molecules with tremendous amount of heat energy . It is represented by fallowing equation.

When heat energy is produce in chemical reaction that reaction is called exothermic process.

Hence respiration is an exothermic process.

2) On what basis is a chemical equation balanced ?

Ans : the chemical equation is balanced on the basis to fulfil the condition of law of conservation of mass .

3) What happens chemically when quicklime is added to water filled in a bucket ?

Ans : when quicklime is added to water in a bucket , it is immediately react with water to form slacked lime and also produce lots of heat with hissing sound .

Quicklime is oxide form of calcium and slacked lime is Hydroxide form of calcium

4) Why should magnesium ribbon be cleaned before burning in air ?

Ans : Magnesium metal is highly reactive element it is easily react with atmospheric oxygen to form magnesium oxide [ MgO] layer . And also magnesium ribbon coated by unwanted impurities .for the purpose to erase the oxide layer and unwanted impurities magnesium metal is cleaned before burning in air .

5) State whether the fallowing statement is true or false

A chemical equation is balanced easily by altering the formula of a reactant or product

Ans : it is false statements

6) What is the wrong with the following chemical equation?

Mg  +O -> MgO

Ans: in above chemical equation oxygen is present in monoatomic from O but is should be present in diatomic form [ molecular  form ] O2

The correct chemical equation is

7) What does the symbol (aq ) represent in a chemical equation?

Ans : The symbol of aq represent in chemical equation is aqueous  solution or A solution made in water .

8) Why is photosynthesis consider an endothermic reaction? .

Ans : In photosynthesis process the sunlight is absorbed throughout the process .it is absorbed as a form of heat energy and carbon dioxide molecule with water get converted to glucose molecule and oxygen  .when heat energy is absorb in chemical reaction then  reaction is called endothermic . Hence photosynthesis is endothermic reaction

9) How will you indicate the fallowing effects in a chemical equation

a) A solution made in water :

A solution made in water is indicated in chemical equation as an aqueous solution . It is written or denoted by aq

It is explained by using fallowing example.

Example : when zinc granules react with dilute sulphuric acid form zinc sulphate solution and hydrogen gas

In above chemical equation the aq is written just below the formula of zinc sulphate solution . It indicate that it is water form of zinc sulphate solution

b) Exothermic reaction :

Exothermic reaction is indicated in chemical equation by writing + heat or + heat energy or + energy on product side .

It is explained by using fallowing example

Example : in respiration process the glucose molecule is combined with oxygen molecule present in body to form carbon dioxide gas and water molecule along with tremendous amount of heat energy.

In above chemical equation heat is produce and it is written in left hand side (product side)

c.) Endothermic reaction :

Endothermic reaction is indicated in chemical equation by writing +heat  or + heat energy or energy  on reactant side .

It is explained by using fallowing example

Example : calcium carbonate is heated and it is decomposed into calcium oxide and carbon dioxide.

In above chemical equation heat is absorb and it is written in reactant side ( left hand side)

10) Translate the following statement into chemical equation and then balanced the equation

a) Hydrogen sulphide gas burns in air to give water and sulphur dioxide

    • Chemical equation of above reaction is :

In above unbalanced chemical equation , at left hand side 2 oxygen molecule is present
and right hand side 3 oxygen molecule is present . Hence multiply O2 by 3 at left hand side and So2 by 2 also H2O by 2 the equation . After that Count the number of atom now in chemical equation 2 hydrogen atom , 1 sulphur atom and 6 oxygen atom is present at left hand side . At right hand side 4 hydrogen atom 2 sulphur atom and 6 oxygen atom is present. Multiply H2S by 3 and write the chemical equation.

The balanced chemical equation is :

b) Phosphorus burns in oxygen to give phosphorous pentoxide.

Chemical equation of above reaction is

In above unbalanced chemical equation count the atom present in it . 4 phosphorous and 2 oxygen atom present at left hand side . 2 phosphorous atom and 5 oxygen atom is present.

Multiply 2 by O2 at left hand side and P2O 5 by 2 and write the equation

Balanced chemical equation is :

c) Carbon disulphide burn in air to give carbon dioxide and sulphur dioxide

Chemical equation of above given word reaction is

In above unbalanced chemical equation 1 carbon atom ,2 oxygen atom present and 2 sulphur atom is present at left hand side . And at right hand side 1 carbon atom ,4 oxygen atom 1 sulphur atom is present.

Multiply O2 by 2 at left hand side and So2 by 2 at right hand side . Write the chemical equation

Balanced chemical equation is :

d.) Aluminium metal replace iron from ferric oxide Fe2O3 giving aluminium oxide and iron

Chemical equation of above reaction is:

In above unbalanced chemical equation , count the number of atom present in it . At left hand side 1 aluminium , 2 iron and 3 oxygen atom is present . At right hand side 2 aluminium ,3 oxygen and 1 iron atom is present

Multiply Fe by 2  at right hand side and multiply Al by 2 then write the chemical equation.

Balanced chemical is :

e) Barium chloride react with zinc sulphate to give zinc chloride and barium sulphate

Chemical equation of above reaction is

This is balance equation , at left hand and right hand side all equal number of atom is present.

11) Write the balanced chemical equation equations for the following reaction :

b) Aluminium + copper chloride —> Aluminium chloride + copper

– chemical equation of above word equation is :

In above reaction , at left hand side 1 aluminium atom , 1 copper atom and 2 chlorine atom is present .at right hand side 1 aluminium atom ,1 copper atom and 3 chlorine atom is present .

Multiply CuCl2 by 3  at product side and write the chemical equation

Balanced chemical equation:

12) Complete and balanced the following equations :

NaOH + ————     —–>     Na2 SO4. + H 2 O

Complete Chemical equation of above word equation is :

In above unbalanced chemical equation , at left hand side 1 sodium atom , 5 oxygen atom , 3 hydrogen atom , and 1 sulphur atom is present . At right hand side 2 sodium atom , 1 sulphur atom ,5 oxygen atom  and 2 hydrogen atom is present

Multiply NaOH by 2 and H2 O by 2 and write the chemical equation

The balanced chemical equation is

b) Ca(OH) 2 + ———— —–> CaCO3 + H2O

– complete chemical equation of above reaction is

This is balance chemical equation .equal number of atom present at product and reactant side.

13) Correct and balanced the following chemical equation

i) Ca + H 2 O —–>     CaOH + H

In above reaction at reactant side , Ca(OH) 2 is present instead of CaOH

The correct chemical equation is

In above unbalanced chemical equation 1 calcium atom, 2 hydrogen atom , 1 oxygen atom is present at reactant side . At product side 1 calcium atom , 4 hydrogen atom , 2 oxygen atom is present Multiply H2O by 2 and write the chemical equation

The balanced chemical equation is

ii) N + H —->     NH3

In above reaction Hmolecule is present in monoatomic from ( H )  it should be present in diatomic form ( H2)

The correct chemical equation is

In above unbalanced chemical equation , at left hand side 2 Nitrogen atom, 2 hydrogen atom is present and at right hand side 1 nitrogen atom and 3 hydrogen atom is present

Multiply H2 by 3 at left hand side and NH3 by 2 at right hand side . Write the chemical equation

The balanced chemical equation is

14 ) Write complete balanced equation for the following reactions :

a) Calcium (solid) + water (liquid)  —–>             calcium hydroxide

(solution) + hydrogen (gas)

-Complete balanced equation of above reaction is

b) Sulphur dioxide (gas) + oxygen (gas) —–>         sulphur trioxide (gas )

    • Complete balanced chemical equation of above reaction is

15) Balanced the following equations:

i) Na + O2 —> Na2O

In above unbalanced chemical equation , at left hand side 1 sodium atom and 2 oxygen atom is present .at right hand side 2 Sodium atom and 1 oxygen atom is present

Multiply 4 by Na and 2 by Na2O , and write the chemical equation

Balanced chemical equation is

ii) H2O2 –> H2 + O2

At reactant side 2 hydrogen atom and 2 oxygen atom is present and at product side 2 hydrogen atom and 3 oxygen atom is presentMultiply H2O 2 by 2 and H2O by 2 and write the chemical equation

iii) Mg (OH )2 + HCl       —>            MgCl 2+ H2O

In above reaction, at reactant side 1 magnesium atom, 3 hydrogen atom , 2 oxygen atom and 1 chlorine atom is present and at product side 1 magnesium atom ,2 chlorine atom , 2 hydrogen atom and 1 oxygen atom is present

Multiply HCl by 2 at reactant side and H2O by 2 at product side. And write the chemical equation

Iv ) Fe +O2  —> Fe2O 3

In above reaction 1 oxygen atom and 2 iron atom is present at reactant side, 3 oxygen atom and 2 iron atom is present at product side

Multiply Fe by 4 and O2 by 3 at reactant side and Fe2O3 by 2 at product side

Balanced chemical equation is

V) Al (OH)3 —> Al2O3+ H2O

– at reactant side 1 aluminium atom ,3 hydrogen atom and 3 oxygen atom is present . At product side 2 aluminium atom , 4 oxygen atom and 2 hydrogen atom is present

Multiply Al( OH )3 by 2 at reactant side and  H2O by 3 at product side

The balanced chemical equation is

Vi) NH3 + CuO         —>           Cu + N2+ H 2O

In above reaction, at reactant side  1 nitrogen atom , 3 hydrogen atom ,1 copper atom and 1 oxygen atom is present , at product side 2 Nitrogen atom , 2 hydrogen atom ,1 copper atom and 1 oxygen atom is present

at reactant side multiply NH3 by 2 and CuO by 3 . And product side multiply Cu by 3 , H2O by 3 . Write the chemical equation

Vii) Al2(SO4 )3+ NaOH           —->           Al( OH )3 + Na2 SO4

In above chemical equation , at reactant side 2 molecule of Aluminium , 3 molecule of sulphur , 13 molecule of oxygen ,1 molecule of hydrogen and 1 molecule of sodium is present . At product side 1 molecule of Aluminium,1 molecule of sulphur, 7 molecule of oxygen ,3 molecule of hydrogen and 2 molecule of sodium is present

At reactant side multiply NaOH by 6 and at product side multiply Al(OH)3by 2 and Na2SO3 by 3 and rewrite the chemical equation

Viii) HNO 3 + Ca (OH) 2 —> Ca(NO 3 ) 2  + H2 O

In above unbalanced chemical equation , at reactant side 3 hydrogen atom , 1 Nitrogen atom ,5 oxygen atom and 1 calcium atom is present . At product side 2 hydrogen atom ,7 oxygen atom, 2 hydrogen atom ,1 Nitrogen atom and 1 calcium atom is present

At product side multiply HNO3 by 2 ,and reactant side H2O by 2 and write the chemical equation

The balanced chemical equation is

ix) NaOH + H2SO4 —> Na2SO4 + H 2O

In above unbalanced chemical equation , at left hand side 1 Sodium atom , 3 hydrogen atom ,5 oxygen atom and 1 sulphur atom is present .at right hand side 2 Sodium atom , 5 oxygen atom 2 hydrogen atom and 1 sulphur atom

For the balance chemical equation , Multiply NaOH by 2 and H 2O by 2  and rewrite the chemical equation

The balanced chemical equation is

X) BaCl 2 + H2SO4 –> BaSO 4 + HCl

– in given reaction at left hand side 1 Barium atom , 2 chlorine atom , 2 hydrogen atom, 1 sulphur atom and 4 oxygen atom is present . At right hand side 1 Barium atom , 1 hydrogen atom, 1 chlorine atom ,1 sulphur atom and 4 oxygen atom is present

To balanced the chemical equation , multiply HCl by 2 rewrite the chemical equation

The balanced chemical equation is

16) fill in the blank with suitable word:

a) chemical equation are balanced to satisfy the law of ————–

– conservation of mass

b) A solution made in water is known as an ————- solution and indicated by the symbol of ———–

– aqueous, aq

17) a) give one example of a chemical reaction?

– chemical reaction in which known substance is converted to new substance . New substance have different chemical properties  Simply it is called reactant is change to product .  It is only rearrangement of atoms .

Example : formation of phosphorous pentoxide is example of chemical reaction .

When phosphorous is burn in oxygen present at atmosphere to form pentoxide

We b) state two characteristics of chemical reaction  which takes place when dilute sulphuric acid is poured over zinc granules

– zinc is highly reactive than Hydrogen element when  dilute sulphuric acid is poured in zinc granules , zinc is easily displaced the hydrogen from sulphuric acid to form hot solution of zinc sulphate and hydrogen gas . when the evolution of hydrogen gas takes place when the test tube is gives brought near the flame it gives popping sound.

In above chemical reaction following  two characteristics are involved

  • Evolution of hydrogen gas takes place .
  • Rise in temperature after adding dilute sulphuric acid in zinc granules .

C) give two characteristics of the chemical reaction which occurs on adding potassium iodide solution to lead nitrate solution .

– when colorless solution of potassium iodide is added in colorless solution of lead nitrate to form yellow precipitate of lead iodide is form . And yellow colored solution of potassium nitrate is form .

In above chemical reaction fallowing two characteristics are involved

  • Formation of precipitation : yellow precipitate of lead iodide is form
  • Change in color : yellow colored solution is formed from colorless solution .

 

18) a) what is a chemical equation? Explain with the help of an example .

– chemical equation is the simple way of representation of chemical reaction by writing formulae of substances , physical state , symbol, also write  temperature include in chemical reaction.

It is simply called short hand method of chemical reaction

Example: zinc metal react with dilute sulphuric acid to form zinc sulphate  and hydrogen gas

It is represented in word equation

Zinc + sulphuric acid ————> zinc sulphate + Hydrogen gas

In above equation

Symbol of zinc is Zn

Formula of sulphuric acid is H 2 SO 4

Formula of zinc sulphate is ZnSO 4

Symbol of Hydrogen gas is  H2

After adding the symbol and formulae , Chemical equation is written as follow

In above chemical equation reactant is written at left hand side  and product is written at right hand side.

Arrow sign (—>) is pointing towards right hand side and it is place in between reactant and product .

Plus sign (+ ) is put between all the reactant and product species .

By applying above condition chemical equation is written .

 

b) Giving example , state the difference between balanced and unbalanced chemical equation

Balanced chemical equation

Unbalanced chemical equation

 The balanced chemical equation means  the equal number of atoms of element present in both the side of reaction The unbalanced chemical equation means the unequal number of atom of element present in both the side of reaction
Same number of molecule present in reactant and product Different number of molecules present in reactant and product

 

Balanced chemical equation follow law of conservation of mass Unbalanced chemical equation does not follow law of conservation of mass
Balanced chemical equation have same quantity of mass of reactant and product Unbalanced chemical equation have different mass of reactant and product
Example :   1) natural gag burns in air ( oxygen ) to form carbon dioxide and water vapor also heat is produced

CH  4 + 2O2   ——–> CO2 + 2H2O

In above reaction equal number of Carbon , hydrogen and oxygen is present at both the side

Hence it is balanced chemical equation

Potassium chlorate  is heated in the presence of manganese dioxide catalyst to form potassium chloride and oxygen gas

2KClO 3  + O3 ——–> 2KCl + 3 O2

In above chemical equation equal number of potassium , oxygen , chlorine atom is present both the side

Example : 1) magnesium ribbon is heated in air with flame to form white powder of magnesium dioxide

Mg + O ——-> MgO

In above reaction at left hand side 1 magnesium atom , 2 oxygen atom is present , at right hand side 1 magnesium atom and 1 oxygen atom is present

Unequal number of oxygen atom is present

Hence it is unbalanced chemical equation

Iron metal react with water molecule to form ferrous oxide and hydrogen

Fe + H 2 O ——-> Fe  3O 4 + H 2

At left hand side 1 ferrous atom ,2 hydrogen atom , 1 oxygen atom is present . At right hand side 3 ferrous atom ,4 Oxygen atom and 2 hydrogen atom is present

Unequal number of oxygen and ferrous atom is present at both the side


 

c) balanced the following chemical equation

I) NH 3 N 2  + H 2

 To balancing the above chemical equation , first to count the no of atoms present in left hand side ( reactant side) and right hand side ( product side )

Reactant side (left hand  side) Product side ( right hand side)
No of N atoms          1          2
No of H atoms          3           2

At left hand side , 1 nitrogen atom and 3 hydrogen atom is present. At right hand side 2 Nitrogen atom and 2 hydrogen atom is present

To equal the nitrogen atom on the both side , multiply NH 3  by 2  and write it 2NH3

 Again count the number of atom present on both the side

Left hand side ( reactant side) Right hand side ( product side)
Number of nitrogen  atom        2 2
Number of hydrogen atom 6 2

Number of nitrogen atom present on both the side is equal only hydrogen. Atom is unequal . There are 6 hydrogen atom present at left hand side and 2 hydrogen atom is present at right hand side , to equal nitrogen atom at left.

 hand side  multiply H 2  by 3 and write 3 H 2

Further count the number of atom present at both the side

Reactant side Product side
No of nitrogen atom 2 2
No of hydrogen atom 6 6

 

Number of atom present in left hand side and right hand side is equal

Balanced equation is

ii) C + CO2 ———> CO

To balancing the number of atoms present on both the side , count the number of atoms present on both the sides

Left hand side ( reactant side ) Right hand side ( product side )
Number of carbon atoms 2 1
Number of oxygen atom 2 1

At left hand side , 2 carbon atom and 2 oxygen atom is present at right hand side , 1 carbon atom and 1 oxygen atom is present

To equal the number of atom of oxygen and carbon atom , multiply CO by 2and write it 2CO.

Again count the number of atoms present on both the side

Left hand side Right hand side
Number of hydrogen atoms 2 2
Number of oxygen atoms 2 2

Equal number of hydrogen and oxygen atom is present at product and reactant side

Balanced chemical equation is

19)  when hydrogen is passed over copper oxide , copper and steam are formed . write a balanced equation for this reaction and state which of the chemicals are :

i) elements ii) compound iii) reactant iv) products v) metals vii) non – metals

– word equation of chemical reaction is

Hydrogen + copper oxide ——-> copper + steam

Chemical equation of reaction is

In above chemical equation , at left hand side 2 hydrogen atom, 1 copper atom , and 1 oxygen atom is present .  at right hand side 2 hydrogen atom , 1 copper atom and 1 oxygen atom is present

Equal  number of hydrogen. Copper and oxygen is present on both the side

Hence balanced chemical equation is

elements : in given reaction hydrogen (H2 ) and copper ( Cu ) element are  present

compound : in given reaction copper oxide ( CuO )   and steam ( H2O ) compound are present

reactant : in above chemical reaction hydrogen ( H 2 ) and copper oxide ( CuO ) reactant are present

product : copper ( Cu )  and steam ( H2O ) product are present

metals : copper ( Cu ) metal is present

non -metal : hydrogen ( H 2 ) is non- metal is present

 

20) a)  what are the various way in which a chemical equation can made mire informative ? Give example to illustrate your answer.

Ans: Chemical equation is the way to express chemical reaction by using their formulae, symbol and physical state .

Three way is use to write chemical equation more informative

  • By denoting the physical state of reactant and product
  • By denoting heat change taking place through out the reaction
  • By indicating the condition under which chemical reaction takes place, It is explained one by one

By denoting the physical state of reaction

There are four physical state are present solid ,liquid , gaseous and aqueous

Solid state is denoted by Symbol s

Liquid state is denoted by symbol l

Gaseous state is denoted by symbol g

Aqueous state is denoted by symbol aq

Physical state is written just below the symbol or formulae of reactant and product

Example: sodium metal is react with water to form sodium hydroxide and hydrogen gas

Sodium + water ——> Sodium hydroxide + hydrogen

2 Na + H 2 O —–> NaOH + H 2          

Sodium metal is present in solid form so it written as Na (s)

Water is in liquid form so it written as H 2O ( l)

Sodium hydroxide is present in aqueous form so it written as NaOH ( aq)

Hydrogen present in gaseous form so it written as H 2 ( g)

After adding the physical state of reactant and product chemical equation is written  as follows

Above equation is becoming more informative after the writing the physical state of element

  • If insoluble product is formed in chemical reaction ( it is precipitated form ) it is written as s . Physical state of insoluble precipitated is solid form hence it is written as s . The short form of precipitated is ppt

By denoting the heat change taking through out the reaction

Two types of reaction is occurs in heat change process .

        • Exothermic chemical reaction
        • Endothermic chemical reaction

Exothermic chemical reaction : the reaction in which heat is released is known as exothermic chemical reaction

In exothermic chemical reaction the heat exchange is denoted by writing + heat ,+ heat energy or + energy  at right hand side ( product side ) .by writing like this it is easy to understand

Example: in respiration process , glucose molecule undergoes combustion with oxygen present in body cell to produce carbon dioxide gas and water molecule with tremendous amount of energy

It is shown by fallowing equation

In above reaction heat is evolved or released  during the respiration process. It is written at product side

Endothermic process – the reaction in which heat is absorb during throughout

the reaction is known as endothermic process .

In endothermic reaction the heat exchange is denoted by writing + heat ,+ heat  energy or + energy at left-hand side ( reactant side ) . By writing like this it is easy to understand us

It is explained by fallowing example

Example: in photosynthesis process , plant absorb sunlight with the help of this energy and chlorophyll pigment  carbon dioxide combine with water

molecule to form glucose molecule and oxygen gas.

In above reaction energy is absorb hence it is written at left hand side

 

To indicating the condition under which reaction takes place :

In  the chemical reaction catalyst , external heat and  temperature  is required to complete the chemical reaction. When heat is given to reaction it denoted by symbol ∆ . It is written over the arrow of equation

  • When catalyst is required to complete reaction it written over the arrow of chemical equation by using their formulae or symbol  .
  • When reaction is complete at certain amount of pressure and temperature it written above the arrow

By written like above explained it is easily understandable to us

Example: potassium chloride is heated in the presence of manganese dioxide catalyst ,it decomposed potassium chloride to form potassium chloride and oxygen

In above reaction heat and catalyst  is required, heat is written over arrow by using symbol ∆  and catalyst manganese dioxide is written  below the arrow by using  their formulae.  MnO 2  . It may be written above or below the arrow .

 

b) write balanced chemical equation of fallowing information

An aqueous calcium hydroxide solution ( lime water ) reacts with carbon dioxide gas to produce a solid calcium carbonate precipitated and water

Ans : word equation of above reaction is

Calcium hydroxide + carbon dioxide ——-> Calcium carbonate + water

Chemical equation is

Balancing chemical equation :  to balancing chemical equation first count the number of atom present at left hand and right hand side

Left hand side Right hand side
Number of carbon atom 1 1
Number of hydrogen atom 2 2
Number of calcium atom 1 1
Number of oxygen atom 4 4

At reactant and product side equal number of atom is present .

Balanced chemical equation is

 

 21) a) what is a balanced chemical equation ? Why should chemical equation is balanced ?

– the chemical equation in which the same or equal number of atom of each and every element is present at product and reactant side is known as balanced chemical equation

The balanced chemical equation is obey law of conservation of mass . In which both the side of element made it equal . chemical reaction is just an rearrangement of atoms . If it not obey the law of conservation of mass it is not  applicable reaction and it does not predictable reaction .if unequal number of reactant and product atom is present if does not occurs .

So the chemical reaction is need to be balanced

b) aluminum burn in chlorine to form Aluminium chloride ( AlCl 3 ) . Write a balanced chemical equation for this reaction

– word equation of above chemical reaction

Aluminium + chlorine ——->Aluminium chloride

Symbol of Aluminium is Al

Symbol of chlorine is Cl

Formula of Aluminium chloride is AlCl3

After writing the formula and symbol in word equation . Chemical equation is becomes as fallow

Balancing chemical equation :

To balanced chemical equation , first count the number of atom present at both the sides

 Reactant ( left hand side)  Product ( right hand side )
No. Of Aluminium atom  1 1
No . Of chlorine atom 2 3

At reactant and product side equal number of Aluminium atom is present . But at reactant side 2 chlorine atom and at product side 3 chlorine atom is present

To equal the chlorine atom multiply Cl 2  by 3 and AlCl 3  by 2  and it is written as . 3 Cl 2 and 2 AlCl 3

Further count the number of atom present both the side

Left hand side

Right hand side

No of chlorine atom 6 6
No . Of Aluminium atom 1 2

At both side equal number of chlorine atom is present

But at left side 1 Aluminium atom and at right hand side 2 Aluminium atom is present. To equal the Aluminium atom multiply Al by 2 and write it 2 Al

Again count the number of atom

Equal number of Aluminium and chlorine is present

Balanced chemical equation is

 

c) Potassium metal react with water to give potassium hydroxide and hydrogen gas . Write a balanced chemical equation for this .

– word equation of above reaction is

Potassium + water —-> potassium hydroxide  + hydrogen

Symbol of potassium is K

Formula of water is H 2O

Formula of potassium hydroxide is KOH

Symbol of hydrogen is H 2

After writing the formula and symbol word equation is becomes as chemical equation

Balancing chemical equation :

To balance the chemical equation , count the number of atom present both the sides

Left hand side

Right hand side

No . Of  potassium atom 1 1
No . Of hydrogen atom 2 3
No of oxygen atom 1 1

Same number of potassium and oxygen atom present at both the sides . It does not need to balanced.

At reactant side 2 hydrogen atom is present and product side 3 hydrogen atom is present

To equal the hydrogen atom , multiply H 2O by 2 and write it 2 H 2O . And multiply KOH by 2 and write as 2 KOH

Chemical equation is becomes as

Again count the number of atom present product and reactant side .

Left hand side Right hand side
No of potassium atom

 

1 2
No of hydrogen atom 4 2
No of oxygen atom 2 4

Same number of oxygen and hydrogen atom is present . But at left hand side 1 Potassium atom and right hand side 2 potassium atom is present

To equal the potassium atom multiply K by 2 and write it 2K

Chemical equation is becomes as

Further count the number of atom present at both the sides

Left hand side

Right hand side

No of potassium atom 2 2
No of hydrogen atom 2 2
No of oxygen atom 4 4

Same number of atoms is present at both the side

Balanced chemical equation is

 

22) a) explain , with example , how the physical state of the reactant and product can be shown in a chemical equation

physical state :  in chemical equation physical state of element or compound is written . It is written to becomes more informative and understand to us . If we write physical state in Chemical reaction it is beneficial to us  and easy to known which compound is solid, liquid or gaseous in state.

There are four physical state present in chemical reaction . I.e. solid ,liquid gaseous and aqueous

Solid form is represented by s

Liquid form is represented by l

Gaseous form is represented by g

Aqueous form is represented by aq

If in chemical reaction insoluble product ( precipitated ) is formed . It is written as s .  Because it is solid form

Physical state of reactant and product is written just below the symbol and formulae of it It is explained by fallowing example

Example : sodium metal react with water to form sodium hydroxide and hydrogen gas

In above reaction

Sodium is present at solid form , it is written as Na ( s)

 H 2 O  is present at liquid form ,it is written as H 2 O (l)

NaOH is present at aqueous form it is written as NaOH

H 2 is present at gaseous form it is written as H 2 (g)

After writing the physical state chemical equation is becomes as

This equation is becomes more informative and understanding  after writing the physical state of product and reactant

b) balanced the fallowing equation and state the symbol

Zn + HCl                          ZnCl 2  + H 2

Ans : to balance the above chemical reaction , we have to do equal number  of atom present  on both the sides

Now , count the number of atom present at reactant and product

Left hand side

( reactant side)

Right hand side

( product side)

No of zinc atom 1 1
No of hydrogen atom 1 2
No of chlorine atom 1 2

Same number of zinc atom is present at both the side . At left hand side 1 hydrogen atom and 1 chlorine atom is present . At right hand side 2 hydrogen atom and 2 chlorine atom is present

To balance the hydrogen and chlorine atom , multiply HCl by 2 and write it as 2 HCl

The chemical equation is becomes as

Again count the number of atom at left hand and right hand side

Left hand side Right hand side
No of zinc atom 1 1
No of hydrogen atom 2 2
No of chlorine atom 2 2

Same number of zinc hydrogen and chlorine atom is present

The balanced chemical equation is

c) convey the fallowing information in the form of balanced chemical equation:

“ An aqueous solution of ferrous sulphate reacts with an aqueous solution of sodium hydroxide to form a precipitate of ferrous hydroxide and sodium sulphate remains in solution.

Ans : word equation of above chemical reaction is

Ferrous sulphate + Sodium hydroxide ——> ferrous hydroxide + sodium Sulphate

Formula of ferrous sulphate is FeSO 4

Formula of sodium hydroxide is NaOH

Formula of ferrous hydroxide is Fe (OH ) 2

Formula of sodium sulphate is Na 2 SO 4

After adding the formulae chemical equation is becomes as

Count the number of atom present on both the sides

Left hand side

Right hand side

No of iron atom 1 1
No of Sulphur atom 1 1
No of oxygen atom 5 6
No of sodium atom 1 2
No of hydrogen atom 1 2

In given chemical equation equal number of iron, Sulphur atom is present

At left hand side 1 sodium atom and 1 hydrogen atom is present

At right hand side 2 sodium atom and 2 hydrogen atom is present

To equal number of atom of both the sides , multiply NaOH by 2 and it written as 2 NaOH .

The chemical equation is becomes as

Again count the number of atom in reactant and product

Same number of atom is present in reactant and product side

Hence balanced chemical equation is becomes as

 

23) Write any two observation in an activity which may suggest that a chemical reaction has taken place . Give an example in support your answer

Ans – in Chemical reaction , when the substance are get converted to new substance which have totally different properties we said that reaction get Completed . It is just rearrangement of atoms .

Fallowing characteristics are shown in Chemical reaction we can easily predict that reaction is complete

  • Evolution of gas
  • Formation of precipitate
  • Change in color
  • Change in temperature
  • Change in state

In which two characteristics are explained below

  • Formation of precipitate : in some chemical reaction precipitate is formed it show that one substance it change to other substance in the insoluble form . precipitate is insoluble aqueous solution in solid form .sometimes it is Colored or white in nature . Precipitate is written in short form as ppt . Ppt can be form by two aqueous solution is add with each other . It is also form by passing gas from an aqueous solution. Precipitate is  easily separate from solution. Formation of ppt is indication of completion of reaction

It is explained by fallowing reaction

e.g. the chemical reaction between sulphuric acid and barium chloride solution to form white ppt of barium sulphate .

Take 5 ml solution of sulphuric acid ( H 2SO 4)in beaker add barium chloride  ( BaCl  2 ) solution in beaker white colour ppt of barium sulphate (BaSO 4)  is formed with hydrochloric acid (HCl) Formation of white ppt of BaSO in beaker indicate that the chemical reaction is takes place . And  BaCl 2 is change in BaSO 4 after react with          H 2SO 4.

  • Change in colour : in some chemical reaction colour changes of solution takes place . It is change from one color to other color or coloured solution to colourless solution Change in colour indicate that the reactant is change to product and reaction is complete. It is explained by fallowing example .

e.g. when Sulphur dioxide gas is passed from acidified potassium dichromate solution . The green coloured solution of potassium dichromate is formed.

Take orange coloured potassium dichromate solution ( KMnO4) in test tube

Passed SO 2 gas through the solution

The orange colour KMnO 4 solution is change into green colour solution

Change in colour indicate the reaction is complete  .

 

24) a) Aluminium hydroxide react with sulphuric acid to form Aluminium sulphate and water write a balance equation for this reaction

–  Word equation of above chemical reaction is

Aluminium hydroxide + sulphuric acid —–>Aluminium sulphate + water

Chemical formula of Aluminium hydroxide is Al ( OH ) 3

Chemical formula of sulphuric acid is H 2 SO 4

Chemical formula of Aluminium sulphate is Al 2SO 4

Chemical formula of water is H2O

After adding the chemical formula , chemical equation is written as

Balancing chemical equation:

First count the number of atom present in reactant and product side

 Reactant side

Product side

No of Aluminium atom 1 2
No of oxygen atom 7 13
No of hydrogen atom 5 2
No of Sulphur atom 1 3

At left hand side 1 Aluminium atom, 7 oxygen atom, 5 hydrogen atom and 1 Sulphur atom is present . At right hand side 2 Aluminium. Atom, 13 oxygen atom 2 hydrogen atom and 3 Sulphur atom is present.

To equal the Aluminium atom at both the side , multiply Al (OH) 3 write it 2Al(OH)3

The chemical equation is becomes as

Again count the number of atom present both the side

Left hand side Right hand side
No of Aluminium atom 2 2
No of oxygen atom 10 13
No of hydrogen atom 8 2
No of Sulphur atom 1 3

In above unequal number of oxygen , Hydrogen and Sulphur atom is present

To equal the Sulphur atom at both the side , multiply H2 SO 4 by  3 and write it 3 H2SO 4

The chemical equation is becomes as

Further count the number atom

Left hand side  Right hand side
No of Aluminium atom 2 2
No of Sulphur atom 3 3
No of hydrogen atom 12 2
No of oxygen atom 18 13

Aluminium and Sulphur atom is same  at both the side .at left hand side 12 hydrogen and 18 oxygen atom is present . At right hand side 2 hydrogen and 13 oxygen atom is present.

To equal the hydrogen atom , multiply H 2O by 6 and write it 6H 2O

The balanced chemical equation is

Now equal number of atom present in reactant and product side

Hence , balanced chemical equation is

b) balanced the following chemical reaction

MnO 2 + HCl —–>MnCl 2  + Cl 2+ H 2O

Ans : firstly count the number of atom present reactant and product side

Left hand side Right hand side
No of manganese atom 1 1
No of hydrogen atom 1 2
No of chlorine atom 1 4
No of oxygen atom 2 2

At left hand side 1 manganese atom, 1 hydrogen atom, 1 chlorine atom and 1 oxygen atom . At right hand side 1 manganese atom, 2 hydrogen atom ,4 chlorine atom and 2 oxygen atom is present

To equal the chlorine atom on both the side , multiply HCl by 4 and write it 4 HCl

The chemical equation become as

Further count the number of atom present in both the side .

No of atoms of  each element Left hand side Right hand side
Manganese 1 1
Hydrogen 4 2
Chlorine 4 4
Oxygen 2 1

In above reaction ,  equal number of chlorine atom is present on both the side . at left hand  1  manganese atom, 4 Hydrogen atom, 2 oxygen atom . At right hand side 1 manganese atom ,2 hydrogen atom and 1 oxygen atom is present

To equal the hydrogen atom , multiply H 2 O by 2 and write it 2 H 2O

The chemical equation is becomes as

Further count the number of atom present on both the side

No of atom of each element Left hand side Right hand side
Manganese 1 1
Hydrogen 4 4
Chlorine 4 4
Oxygen 2 2

In above reaction , equal number  various type of atom  is present on both the side

The balanced chemical equation is

 

25) Write the balanced equations for the fallowing reaction , and add the state symbol :

a) magnesium carbonate reacts with hydrochloric acid produce magnesium chloride , carbon dioxide and water

Ans : word equation of above chemical reaction is .

Magnesium carbonate + hydrochloric acid —-> magnesium chloride + carbon dioxide + water

Chemical formula of magnesium carbonate  is MgCO 3

Chemical formula of hydrochloric acid HCl

Chemical formula of magnesium chloride is MgCl  2

Chemical formula of carbon dioxide is  CO 2

Chemical formula of water is H 2O

After adding the chemical formulae , chemical equation is written as

Balancing chemical equation:

First count the  number of atom present on reactant and product side

No of atoms of each and every element Left hand side   Right hand side
Magnesium 1 1
Carbon 1 1
Oxygen 3 3
Hydrogen 1 2
Chlorine 1 2

In chemical reaction same number of magnesium , carbon ,oxygen and hydrogen atom is present at both the sides . Only 1 chlorine atom is present at left hand side and 2 chlorine atom is present at right hand side .

To equal the chlorine atom , multiply HCl by 2 write it as 2 HCl

Thus chemical equation is becomes as

Again count the number of atom present on both the sides .

Equal number of atom is present at both the side

The balanced chemical equation is

  • Physical state :

Physical state of reactant and product is given below

MgCO 3  is an aqueous solution , it is write as MgCO 3 ( aq)

HCl is in liquid form , it is written as HCl ( l)

MgCl 2  is in aqueous form , it is written as MgCl 2 ( aq )

CO 2 is in gaseous form , it is written as CO 2 ( g)

H 2 O  is in liquid form , it is written as H 2O ( l)

After adding the physical state , chemical equation is becomes as

b) sodium hydroxide reacts with sulphuric acid to produce sodium sulphate and water .

Ans : word equation of chemical reaction is

Sodium hydroxide + sulphuric acid ——-> Sodium sulphate + water

Chemical formula of sodium hydroxide is NaOH

Chemical formula of sulphuric acid is H 2SO 4

Chemical formula of sodium sulphate is Na 2SO 4

Chemical formula of water is H 2O

After adding the chemical formulae , chemical equation is written as

Balancing chemical equation :

First count the number of atom present on both the side

No of atom of each element Left hand side Right hand side
Sodium 1 2
Hydrogen 3 2
Oxygen 5 5
Sulphur 1 1

In chemical reaction same number of Sulphur atom is present on both the side , at left hand side 1 sodium atom, 3 hydrogen atom ,5 Oxygen atom is present .at right hand side 2 hydrogen atom,2 sodium atom and 5 oxygen atom is present

To equal the sodium atom multiply NaOH by 2 and write it 2NaOH this chemical equation is becomes as .

Again count the number of atom is present on both the side .

No of atom of each element Left hand side Right hand side
Sodium 2 2
Hydrogen 4 2
Oxygen 6 5
Sulphur 1 1

At left hand side 4 Hydrogen atom,6 oxygen atom is present . At right hand side 2 hydrogen , 5 oxygen atom is present .equal number of sodium and Sulphur atom is present

To equal the hydrogen atom , multiply H 2O by 2 write it as 2 H 2O

This chemical equation is becomes as

Further count the number of atom present on both the sides

Equal number of atom  present on reactant and product sides

The chemical equation is becomes as

Physical state :  physical state symbol of reactant and product is fallow

NaOH is in aqueous form   ,it written as NaOH (aq)

H 2SO 4  is in aqueous form , it is written as H 2SO 4 ( aq)

Na2SO 4  is in aqueous form , it is written as Na2SO 4  ( aq )

H2O is in liquid form , it is written as H 2O ( l)

After adding the state symbol , chemical equation is becomes as

26) Carbon monoxide react with hydrogen under certain conditions to form methanol ( CH3OH ). Write a balanced chemical equation this reaction indicating the physical states of reactants and product as well as the condition under which the reaction takes place .

Ans : word equation for the chemical reaction is

Carbon monoxide + hydrogen —-> methanol

Chemical formula of carbon monoxide is CO

Chemical formula of hydrogen is H 2

Chemical formula of methanol is CH 3 OH

After writing the chemical formula , the chemical equation becomes as

Above reaction is proceed under certain condition , this condition is explained below

Condition : the reaction is takes place at 300 atm pressure  in the presence of zinc oxide and chromium oxide catalyst heated at 300 0 C temperature to form methanol

This condition is written above and below the arrow

300 atm pressure and 300 0 C temperature write over the arrow and mixture of catalyst ( ZnO + CrO3) is write below the arrow.

The reaction is becomes as follows

Balancing chemical equation :

Count the number of atom present on both the sides

No of atoms of each element Left hand side Right hand side
Carbon 1 1
Oxygen 1 1
Hydrogen 2 4

In chemical reaction ,  same number of carbon and oxygen molecule is present on both the sides .at left hand side 2 hydrogen atom is present and at right hand side 4 hydrogen atom is present.

To equal the number of Hydrogen atom multiply H 2  by 2 write it 2 H 2

Thus chemical equation is becomes as

Again count the number of atom present on reactant and product side

Equal no of carbon, oxygen and hydrogen is present at both the sides

Balanced chemical equation is

State symbol :  the indication of physical state is given as follows

CO is in gaseous form ,so it is written as CO ( g)

H 2 is in gaseous form , so it is written as H 2 (g )

CH 3OH is in liquid form , so it is written as CH 3OH ( l)

After adding the state symbol chemical equation is becomes as

 

27) a) potassium chromate ( KClO 3 ) on heating forms potassium chloride and oxygen . Write a balanced for this indication the evolution of gas .

Ans : word equation of above chemical reaction is

Potassium chromate ——-> potassium chloride + oxygen

Chemical formula of potassium chromate is KClO3

Chemical formula of potassium chloride is KCl

Symbol of oxygen is O 2

After Writing  the chemical formulae , and chemical equation is becomes as

In above reaction , potassium chromate is strongly heated and after thermal decomposition to form Potassium chloride and oxygen Gas.

Oxygen gas is evolved during the decomposition . So it is indicated by writing up ward arrow just near the oxygen atom.

Balancing chemical equation :  equal the number of atoms present in both the side by using stoichiometry coefficient

First count the number of atom present on both the sides

No of atoms of each element Left hand side Right hand aide
Potassium 1 1
Chlorine 1 1
Oxygen 3 2

Equal number of Potassium and chlorine atom is present on both the side . At reactant side 3 oxygen atom is present and product side 2 oxygen atom is present

To equal the oxygen atom ,  multiply KClO 3 by 3 and write it as 3 KClO 3  at left hand side .at right hand side multiply O2by 3 write it as 3O 2

Chemical equation is becomes as

further count the number of atom present on both the sides

No of atoms of each element Left hand side Right hand side
Potassium 2 1
Chlorine 2 1
Oxygen 6 6

Again count the number of atom present in reactant and product side

Same number of oxygen atom is present on both the sides At left hand side 2 potassium atom and 2 chlorine atom is present and. At right hand side 1 Potassium atom and 1 chlorine atom is present

To equal the potassium and oxygen atom on right hand side , multiply KCl by 2 and write it as 2 KCl

Thus chemical equation is becomes as

Further count the number of atom

Equal number of Potassium , chlorine and oxygen is present on reactant and product side

Hence balanced chemical equation is

b) Rewrite the following information in the form of balanced chemical equation

Magnesium burns in carbon dioxide to form magnesium oxide and carbon

Ans :.  Word form of above reaction is

Magnesium + carbon dioxide —–> magnesium oxide + carbon

Chemical formula of magnesium is Mg

Chemical formula of carbon dioxide is CO

Chemical formula of magnesium oxide is MgO

Symbol of carbon is C

After adding the symbol and formulae Chemical equation is written as

Balancing chemical equation:

Count the number of atom present on both the sides

No of atom of each element Left hand side Right hand side
Magnesium 1 1
Carbon 1 1
Oxygen 2 1

Same number of magnesium and carbon atom is present on reactant  and product side. At left hand side 2 oxygen atom is present and  at right hand side 1 oxygen atom .

To equal the oxygen atom multiply MgO by 2 and write it as 2MgO

Thus chemical equation is becomes as

Again count the number of atom present on both the sides

No of atoms of each element Left hand side Right hand aide
Magnesium 1 2
Carbon 1 1
Oxygen 2 2

Same number of carbon and oxygen atom is present on both the sides . Only magnesium atom is unequal . At left hand side 1 magnesium atom is present and at right hand side 2 magnesium atom is present.

To equal the magnesium atom multiply Mg by 2 and write it as 2Mg

The chemical equation is becomes as

Further count the number of atom present on reactant and product side

Same number of carbon , oxygen and magnesium atom is present

Hence balanced chemical equation is as fallow .

28) a) substitute the formula for name and balanced chemical equation

Calcium carbonate reacts with hydrochloric acid to produce calcium chloride ,water and carbon dioxide gas .

Ans : word equation of chemical reaction is

Calcium carbonate + hydrochloric acid —–> calcium chloride + water

Chemical formula of calcium carbonate is CaCO 3

Chemical formula of hydrochloric acid is HCl

Chemical formula of calcium chloride is CaCl 2

Chemical formula of water is H 2O

Add the chemical formula of reactant and product

Chemical equation is becomes as

Balancing chemical equation : count the no of atoms present on both the sides

No of atom of each element Left hand side Right hand side
Calcium 1 1
Carbon 1 1
Oxygen 3 3
Chlorine 1 2

equal number of calcium , carbon and oxygen is present on both the side . At left hand side 1 Chloride atom and right hand side 2 chlorine atom is present

To equal chlorine atom , multiply HCl by 2 and write it 2HCl

Thus chemical equation is becomes as

Further count the number of atom present at left hand and right hand side

Equal number of carbon, calcium oxygen and chlorine atom is present in reactant and product side

Balanced chemical equation is

b) Write the balanced chemical equation with state symbol for the fallowing reaction :

Sodium hydroxide solution reacts with hydrochloric acid solution to produce sodium chloride solution and water .

Ans : word equation of above chemical reaction is

Sodium hydroxide + hydrochloric acid ——> sodium chloride + water

Chemical equation of reaction is

Balancing chemical equation :

Count the atoms present on both the side

No of atoms of each element

Left hand side

( reactant side )

Right hand side

( product side)

Sodium 1 1
Oxygen 1 1
Hydrogen 2 2
Chlorine 1 1

Same number of sodium ,oxygen , hydrogen and chlorine atom is present

Hence balanced chemical equation is

Sodium hydroxide is present in aqueous solution form , so it is written as NaOH (aq)

Hydrochloric acid is present in aqueous form , so it written as HCl (aq)

Sodium chloride is present in aqueous form , it is written as NaCl ( aq)

Water is present in solid form , it is written as H 2O ( l)

After adding the symbol chemical equation is becomes as

 

29) Ammonia reacts with oxygen to form nitrogen and water write a balanced chemical equation for this reaction. Add the state symbol for all the reactant and product

Ans : Word equation of chemical reaction is

Ammonia + oxygen ——> nitrogen + water

Chemical equation of above reaction is

Balancing chemical equation :

Count the number of atom present on both the sides

No of atoms of each element

Left hand side

Right hand side

Nitrogen 1 2
Oxygen 2 1
Hydrogen 3 2

At left hand side 1 hydrogen atom, 2 oxygen atom and 3 hydrogen atom is present , at right hand side 2 Nitrogen atom , 1 oxygen atom and 2 hydrogen atom is present

To equal all the atoms present in reactant and product side . At left hand side multiply 4 by NH 3 , O 2  by 3 and right hand side N 2  by 2 and  H 2 O by 6

Thus chemical equation becomes as

Ammonia is present at gaseous form it is written as NH 3 ( g)

Oxygen is present in gasouse form it is written as O 2 ( g)

Nitrogen is present in gaseous form it is written as N 2 (g)

Water is present at liquid form it is written as H 2O ( l)

After adding state symbol chemical equation is becomes as.

 

30) Write a balanced chemical equation for process of photosynthesis giving the physical state of all the substance  involve and condition of the reaction .

Ans :  in the process of photosynthesis , carbon dioxide molecule is react with water molecule in sunlight and chlorophyll pigment gives glucose molecule and Oxygen gas.

This reaction is carried out in the presence of heat energy . This heat energy is absorbed from sunlight.  Also required chlorophyll pigment to completionreaction . This two condition is  required to complete reaction . This is written above and below the arrow in chemical reaction.

Balancing chemical reaction:

Count the no of atoms present on both the sides

No of atoms of each element

Left hand side

Right hand aide

Carbon 1 6
Oxygen 3 8
Hydrogen 2 12

At left hand side 1 carbon atom , 3 oxygen atom , 2 hydrogen atom is present at right hand side 6 carbon atom , 8 oxygen atom and 12 hydrogen atom is present

To balanced the carbon atom multiply CO 2 by 6 and write 6 CO 2

Chemical equation is becomes as

Again count the number of atom present on reactant and product side

No of atoms of each element Left hand side Right hand side
Carbon 6 6
Hydrogen 2 12
Oxygen 13 8

Same number of carbon atom is present on both the sides. At left hand side 2 hydrogen atom and 13 oxygen atom is present at right hand side 12 hydrogen atom and 8 oxygen atom is present

To equal the hydrogen atom multiply H 2O by 6 write it as 6 H 2O . Thus chemical equation is becomes as

Further count the number of atom present on both the sides

No of atoms of each element

Left hand aide

Right hand side

Carbon 6 6
Hydrogen 12 12
Oxygen 18 8

Same number of carbon and oxygen atom is present on both the sides . But at reactant side 18 oxygen atom is present and product side 8 oxygen atom is present

To equal the oxygen atom , multiply  O 2by 6 and write it as 6 O 2

Chemical equation is becomes as

Again Count the number of atom

Equal number of hydrogen , oxygen and carbon atom is present

Hence balanced chemical equation is

Carbon dioxide is present in gaseous form it is written as CO 2 ( g)

Water is present in liquid form it is written as H 2O ( l)

Glucose is present in aqueous form it is written as C 6H 12 O 6 ( aq)

Oxygen is present in gaseous form it is written as O 2 ( g)

After adding the physical state , chemical equation is becomes as

 

31) translate the fallowing statement into chemical equation and then balanced it. Barium chloride solution reacts with Aluminium sulphate solution to form a precipitate of barium sulphate and Aluminium chloride Solution

Ans: word equation of above reaction is

Barium chloride + Aluminium sulphate —-> barium sulphate + Aluminium chloride

Chemical equation of above reaction is

Balancing chemical equation:

First count the number of atom present on both the sides

No of atom of each element Left hand side Right hand side
Barium 1 1
Chlorine 2 3
Aluminium 2 1
Sulphur 3 1
Oxygen 12 4

At left hand side 1 Barium atom., 2 chlorine atom ,2 Aluminium atom ,3 Sulphur atom and 12 oxygen atom is present . At right hand side 1 Barium atom, 3 chlorine atom , 1 Aluminium atom , 1 Sulphur atom and 4 oxygen atom is present

To equal the Sulphur atom ,multiply BaSO 4  by 3 and write it as 3 BaSO 4

The chemical equation is becomes as

Again count the number atom present on both the sides

No of atom of each element

Left hand side

Right hand side

Barium 1 3
Aluminium 2 1
Sulphur 3 3
Oxygen 12 12
Chlorine 2 3

At left hand side equal number of oxygen atom is present . 2 chlorine atom is present on reactant side and 3 chlorine atom is present on product side

To equal the chlorine atom multiply BaCl 2 by 2 and AlCl 3 by 3

Thus chemical equation is becomes as

Further count the number of atom is present on reactant and product side

No of atom of each element Left hand side Right hand side
Barium 3 3
Aluminium 2 2
Chlorine 6 6
Oxygen 12 12
Sulphur 3 3

Equal number of atom is present on both the sides

Hence balanced chemical equation is

 

32) When Potassium nitrate is heated , it decomposed into potassium nitrite and oxygen . Write a balanced equation for this reaction and add state symbol of the reactants and product

Ans : word equation of above chemical reaction is

Potassium nitrate —–> potassium nitrite + oxygen

Chemical equation of above reaction is

Balanced chemical equation:

Count the number of atom present on both the sides

No of atoms of each element Left hand side Right hand side
Potassium 1 1
Nitrogen 1 1
Oxygen 3 4

Same number of Potassium and nitrogen atom is present on both the sides. At left hand side 3 oxygen atom and at right hand side 4 oxygen atom is present

To equal the oxygen atom , multiply KNO 3 by 2 and KNO 2 by 2 and chemical equation is becomes as

Again count the number of atom present on reactant and product side

No of atoms of each element

Left hand side

Right hand side

Nitrogen 2 2
Potassium 2 2
Oxygen 6 6

Equal number of atom is present on both the sides

Hence balanced chemical equation is

KNO 3 is present at solid form it is written as KNO 3 ( s)

KNO 2 is present at solid form it is written as KNO 2 (s)

O 2 is present in gaseous form it is written as O 2 (g)

After adding physical state Chemical equation is becomes as

  • Long type questions :

33) a) What is mean by chemical reaction ? Give with the help of an example .

Answer :

The chemical reaction in which one substance is get converted to new substance.

The process in which the rearrangement of atoms of reactant species takes place to form a new compound which have totally different properties is called chemical reaction.

In chemical reaction, breaking of atoms does not takes place only rearrangement of atoms is possible.

During chemical reaction breaking of one bond between reactant species to form new bond in new substance

The substance in which rearrangement of atoms and breaking of bonds takes place is called reactant

The new  substance which is formed after rearrangement of atoms is called product

Reactant and product have totally different properties.

  • Chemical reaction is discuss from following example

When a magnesium ribbon is heated , in air with dazzling white flame from a white powder of magnesium oxide

Magnesium + oxygen             —->                     Magnesium oxide

(Ribbon)         ( in air )                             (White powder)

Mg       +       O 2                      —->            MgO

In above reaction, two reactant molecule magnesium and oxygen is present and product magnesium oxide is formed . Magnesium oxide have totally different properties than magnesium and oxygen.

  • Chemical reaction is just not seen in laboratory . It is seen in daily life fallowing example are chemical which is seen in daily life
  1. Souring of milk
  2. Formation of crud from milk
  3. Cooking of food
  4. Digestion of food in our body
  5. Process of photosynthesis
  6. Process of respiration
  7. Rusting of iron
  8. Burning of fuels
  9. Burning of wax candle

In all the reaction chemical changes takes place.

This is all about chemical reaction

b) Give one example of a chemical reaction is characterized

I) evolution of gas : in some chemical reaction evolution of gas takes place .this indicate that chemical reaction takes place .

Example : when magnesium metal is react with a dilute sulphuric acid form magnesium sulphate and hydrogen gas

ii) Change in colour : in some chemical reaction change in colour of solution takes place .it is indication of chemical reaction occurs

It is explained by fallowing example

e.g. when sulphur dioxide gas is passed through acidified potassium  dichromate solution . The orange colour of potassium dichromate is change to green colour

From above discussion , we easily said that the reaction of sulphur dioxide with potassium dichromate is characterized by change in colour

Iii) Formation of precipitated : in many chemical reaction precipitated is formed formation of precipitated is indicated that chemical reaction occurs.

It is explained by fallowing example .

e .g. when barium chloride solution is added in dilute sulphuric acid solution to formed white coloured of ppt barium sulphate

Hence the reaction of barium chloride with sulphuric acid solution is easily characterized by a formation of white ppt of BaSO4

Iv) Change in temperature :  in many chemical reaction temperature is changed .it is indication by solution becoming hot or evolution of heat takes place or absorption of heat takes place or absorption of heat takes place during reaction .

It is explained by fallowing example

When carbon is burn in air (Atmosphere ) to form carbon dioxide with lots of heat.

It is exothermic type of reaction in which heat is released or evolved.

V) Change in state : in some cases state of substance is changed . It changes from solid liquid or liquid to gas or solid to gas. From this conversion chemical reaction is easily characterised.

It is explained by fallowing example

  • When wax candle is burn then water and carbon dioxide is formed.

Wax candle is in solid State, water is in liquid state and carbon dioxide is gaseous form .

State is changed from solid to gas and liquid hence burning of wax candle is characterised by change in state.

34) a) State the characteristics of chemical reaction

In chemical reaction one substance is get converted to new substance have different properties. It is we simply called reaction get completed

Simply reactant species get converted to product species, chemical reaction is done.

By observing some changes chemical reaction is characterised .the importance characteristics is given below

I) Evolution of gas

II) Change in colour

III) Formation of precipitated

IV) Change in temperature

V) Change in state.

Now the answer same as 33B above

b) State one characteristics each of the chemical reaction which takes place when

I) Dilute hydrochloric acid is added to sodium carbonate :

– hydrochloric acid is react with sodium carbonate to form sodium chloride , water and carbon dioxide gas

In above reaction carbon dioxide gas is formed which is evolved in atmosphere

Hence above reaction is characterised by evolution of gas.

ii) lemon juice is added gradually to potassium permanent solution:

Lemon juice contain citric acid .  When citric acid is react with potassium permanent solution, the purple colour of potassium permanent solution is change to  colourless solution

Colour change is takes place from purple colour to colourless

Above reaction is characterised by change in colour

Iii) Dilute sulphuric acid is added to barium chloride solution

When dilute  sulphuric acid is added to barium chloride solution to form white coloured precipitated of barium sulphate along with hydrochloric acid solution.

In given chemical reaction  of white colour precipitated of barium sulphate is formed

Above chemical reaction is characterised by formation of precipitate

Iv) Quicklime is treated with water ;

When quicklime ( calcium oxide ) is added in warm water slacked lime ( calcium hydroxide ) is formed and release large amount of heat .

After adding quicklime with water Temperature is gradually increase and bubbles of Ca(OH)2  is formed . It is exothermic reaction

Above reaction is characterised by change in temperature

V) Wax is burn in the form of a candle :

When candle is burn in air water and carbon dioxide gas is formed

Water is present in liquid state and carbon dioxide is present in gaseous form .

Hence state is changes from solid to liquid and gas

Above process is characterised by change in state

35)

a) What do you understand by exothermic and endothermic reaction

Exothermic reaction : the reaction in which heat is released or evolved during the process is known as exothermic reaction .

Evolution of heat is taking place in the form of increasing temperature of reaction or in the form of energy

Simply we said that when the reaction in which energy is produced is known as exothermic reaction.

The meaning of exothermic is : exo means –produce or released

Thermic means –  heat or energy

The exothermic reaction is Indicated by writing + heat , + heat energy or + Energy on right hand side i.e. product side

By writing like this it is easily understand to us For identification of reaction .

Example : when natural gas ( methane ) is burn with oxygen  present in air it form carbon dioxide gas and water with large amount of heat

Natural gas + Oxygen      —->    Carbon dioxide + Water + Heat

The burning of natural gas is exothermic process because in throughout the process hart is given out . It is denoted by writing heat is product side.

Some other examples of exothermic reaction is

Combustion of food in body ( respiration )

Combustion of fuels like wood ,coal , kerosene petrol , diesel

Burning of magnesium wire ,heat or light  energy is released

Formation of ammonia from nitrogen and hydrogen

Endothermic reaction: The reaction in which heat energy is absorb during process is called endothermic reaction.

The meaning of exothermic is

Endo means absorb or consume

Thermic means heat or temperature

Simply we called consumption of energy or consumption of heat is endothermic reaction

The endothermic reaction is indicated by written + heat , + heat energy  or + energy at left hand side ( reactant side )

It is explained by fallowing example

The nitrogen and oxygen are heated at high temperature ( about 3000C ) and combine to form nitrogen monoxide and lots of heat is consuming through out the process .

Heat is absorbed hence it is written at left hand side .

The formation of nitrogen monoxide is endothermic process .

  • Some other examples of endothermic reaction is given fallow

Decomposition of calcium carbonate

Electrolysis if water

Photosynthesis reaction in plant

b) Give one example of an exothermic and one example of an endothermic reaction

– Exothermic reaction: the reaction in which heat is released is known as exothermic reaction .

Example of exothermic reaction is

When nitrogen is combine with hydrogen gas to form ammonia
Heat is released through out the process . It is written at right hand side ( product side)

Formation of ammonia is exothermic reaction

Endothermic reaction: the reaction in which heat is absorbed is known as endothermic reaction

Example of endothermic reaction is

When carbon molecule is reacts with sulphur to form carbon sulphide During the formation of carbon sulphide is a endothermic reaction

Heat is absorb during the process.

C) Which of the fallowing are endothermic reactions and which of the exothermic reaction

I) Burning of natural gas

When natural gas ( methane ) is burn in oxygen ( in air ) to form carbon dioxide, water molecule and heat

CH4 + 2O2 —> CO2 + 2H2O + Heat

The heat is released during the process

Hence it is exothermic reaction.

ii) Photosynthesis :

In photosynthesis process the carbon dioxide gas and water is combined with each other in the presence of chlorophyll pigment (green colour pigment ) and sunlight to form glucose molecule and oxygen gas

6CO2 (g) + 6H2O —> C6H12O6 + 6O2(g)

In photosynthesis process heat is absorbed throughout the process

Hence photosynthesis is endothermic reaction.

iii) Electrolysis of water

When external heat is provided to water molecule is decomposed into oxygen and hydrogen gas is known as electrolysis process

2H2O —> O2 + 2H2

In electrolysis heat  is consumed.

Hence it is endothermic reaction.

iv) Respiration :

In respiration process the glucose molecule and oxygen is combined with each other and oxidation of glucose molecule is taking place to form carbon dioxide and water molecule along with large amount of heat

C6H12O6 (aq) + 6O2 (g)  —> 6CO2 (g) + H2O + Energy

Heat is released in respiration process.

Hence respiration is exothermic reaction.

V) Decomposition of calcium carbonate :

The calcium carbonate molecule is heated and decomposed into calcium oxide molecule  and carbon dioxide gas

Throughout the process external heat is provided

Hence decomposition of calcium carbonate is exothermic reaction.

 

Part 2 Solution 

 

SAQ2

Short Type and Long Type Answer Solution:

long type questions answer chemistry chemical reactions and equations
Updated: July 7, 2021 — 10:31 pm

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