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 2 ——-> 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
- Souring of milk
- Formation of crud from milk
- Cooking of food
- Digestion of food in our body
- Process of photosynthesis
- Process of respiration
- Rusting of iron
- Burning of fuels
- 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
For more Chapter solution, click below