Samacheer Kalvi 10th Science Types of Chemical Reactions Chapter 10 Pdf
Tamilnadu Board Samacheer Kalvi 10th Science Types of Chemical Reactions Chapter 10: Tamilnadu State Board Solution Class 10 Science Chapter 10 – Types of Chemical Reactions.
Samacheer Kalvi 10th Science Types of Chemical Reactions Chapter 10: Overview
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Board |
Samacheer Kalvi |
| Class |
10 |
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Subject |
Science |
| Chapter |
10 |
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Chapter Name |
Types of Chemical Reactions |
Samacheer Kalvi 10th Science Types of Chemical Reactions Chapter 10 Types of Chemical Reactions
I.) Choose the correct answer.
1.) H2(g) + Cl29(g) → 2HCl(g) is a
a) Decomposition Reaction
b) Combination Reaction
c) Single Displacement Reaction
d) Double Displacement Reaction
Ans:b.) Combination Reaction
Because, in combination reaction two or more reactants combines to form the product.
2.) Photolysis is a decomposition reaction caused by ___________
a) heat
b) electricity
c) light
d) mechanical energy
Ans: c.) light
Because, photolysis occurs by using light.
3.) A reaction between carbon and oxygen is represented by C(s) + O2(g) → CO2(g) + Heat. In which of the type(s), the above reaction can be classified?
(i) Combination Reaction
(ii) Combustion Reaction
(iii) Decomposition Reaction
(iv) Irreversible Reaction
a) i and ii
b) i and iv
c) i, ii and iii
d) i, ii and iv
Ans:d.) i, ii and iv
Because, in the given reaction two reactants combines and formed the product hence it acts as a combination reaction.
Also, heat is evolved with CO2 gas and hence combustion reaction.
And it is not a reversible reaction and hence it is irreversible.
4.) The chemical equation Na2SO4(aq) + BaCl2(aq) → BaSO4(s)↓ + 2NaCl(aq) represents which of the following types of reaction?
a) Neutralisation
b) Combustion
c) Precipitation
d) Single displacement
Ans:c) Precipitation
Because, in this reaction the precipitate of BaSO4 is formed.
5.) Which of the following statements are correct about a chemical equilibrium?
(i) It is dynamic in nature
(ii) The rate of the forward and backward reactions are equal at equilibrium
iii) Irreversible reactions do not attain chemical equilibrium
(iv) The concentration of reactants and products may be different
a) i, ii and iii
b) i, ii and iv
c) ii, iii and iv
d) i, iii and iv
Ans: a) i, ii and iii
6.) A single displacement reaction is represented by X(s) + 2HCl(aq) → XCl2(aq) + H2(g). Which of the following(s) could be X.
(i) Zn
(ii) Ag
(iii) Cu
(iv) Mg.
Choose the best pair.
a) i and ii
b) ii and iii
c) iii and iv
d) i and iv
Ans:d)i and iv
Because, Zn and Mg involves in single displacement reaction and displaces the single ion.
7.) Which of the following is not an “element + element → compound” type reaction?
a) C(s) + O2(g) → CO2(g)
b) 2K(s) + Br2(l) → 2KBr(s)
c) 2CO(g) + O2(g) → 2CO2(g)
d) 4Fe(s) + 3O2(g) → 2Fe2O3(s)
Ans:c) 2CO(g) + O2(g) → 2CO2(g)
Because, in this reaction CO is the reactant compound not an element.
8.) Which of the following represents a precipitation reaction?
a) A(s) + B(s) → C(s) + D(s)
b) A(s) + B (aq) → C (aq) + D (l)
c) A (aq) + B (aq) → C(s) + D (aq)
d) A (aq) + B(s) → C (aq) + D (l)
Ans:c) A (aq) + B (aq) → C(s) + D (aq)
Because, in precipitation reaction two aqueous solutions mix together and a solid precipitate is formed.
9.) The pH of a solution is 3. Its [OH–] concentration is
a) 1 × 10–3 M
b) 3 M
c) 1 × 10–11 M
d) 11 M
Ans: c) 1 × 10–11 M
10.) Powdered CaCO3 reacts more rapidly than flaky CaCO3 because of ___________.
a) large surface area
b) high pressure
c) high concentration
d) high temperature
Ans:a) large surface area
II.) Fill in the blanks
1) A reaction between an acid and a base is called _________________.
Ans: A reaction between an acid and a base is called neutralization.
2) When lithium metal is placed in hydrochloric acid, ________ gas is evolved.
Ans: When lithium metal is placed in hydrochloric acid, hydrogen gas is evolved.
3) The equilibrium attained during the melting of ice is known as ___________.
Ans:The equilibrium attained during the melting of ice is known as Physical equilibrium.
4) The pH of a fruit juice is 5.6. If you add slaked lime to this juice, its pH _____________ (increse/decrese)
Ans:The pH of a fruit juice is 5.6. If you add slaked lime to this juice, its pH increases.
5) The value of ionic product of water at 250 C is _____________.
Ans:The value of ionic product of water at 250 C is 1*10-14.
6) The normal pH of human blood is _________
Ans: The normal pH of human blood is7.4.
7) Electrolysis is type of _______________ reaction
Ans: Electrolysis is type of decompositionreaction
8) The number of products formed in a synthesis reaction is _________
Ans:The number of products formed in a synthesis reaction isone.
9) Chemical volcano is an example for _______________ type of reaction
Ans:Chemical volcano is an example for decomposition reaction type of reaction
10) The ion formed by dissolution of H+ in water is called _______________
Ans:The ion formed by dissolution of H+ in water is called hydronium ion.
III.) Match the following
Ans:
1) NH4OH(aq) + CH3COOH(aq) → CH3COONH4(aq) + H2O(l) : Neutralization
2) Zn(s) + CuSO4(aq) → ZnSO4(aq) + Cu(s) : Single displacement
3) ZnCO3(s) + Heat → ZnO(s) + CO2(g) : Thermal decomposition
4) C2H4(g) + 4O2(g) → 2CO2(g) + 2H2O(g) + Heat : Combustion
IV.) True or False: (If false give the correct statement)
1) Silver metal can displace hydrogen gas from nitric acid.
Ans: False
Correct statement: All the metals below hydrogen does not react with nitric acid.
2) The pH of rain water containing dissolved gases like SO3, CO2, and NO2 will be less than 7.
Ans: True
3) At the equilibrium of a reversible reaction, the concentration of the reactants and the products will be equal.
Ans: False
Correct statement: At equilibrium the rate of forward reaction is equal to the rate of backward reaction.
4) Periodical removal of one of the products of a reversible reaction increases the yield.
Ans: True
5) On dipping a pH paper in a solution, it turns into yellow. Then the solution is basic.
Ans: True
V.) Short answer questions:
1.) When an aqueous solution of potassium chloride is added to an aqueous solution of silver nitrate, a white precipitate is formed. Give the chemical equation of this reaction.
Ans:
When an aqueous solution of potassium chloride is added to an aqueous solution of silver nitrate, a white precipitate of silver nitrate AgCl is formed and the reaction is given below.
KClaq+ AgNO3aq → AgCl ↓+ KNO3aq
Potassium Chloride Silver Nitrate Silver Chloride
2) Why does the reaction rate of a reaction increase on raising the temperature?
Ans:
The rate of reaction increases as the temperature is increased because, when heat energy is provided to the reactant molecule then there will be more breaking of bonds happens which speeds up the reaction.
For example: at room temperature, calcium carbonate reacts with hydrochloric acid slowly.
But when this reaction mixture is heated the rate of reaction will be increased.
3) Define combination reaction. Give one example for an exothermic combination reaction.
Ans:
Combination reaction:
In this reaction two or more reactants combines to form the product. Combination reaction is also called as synthesis reaction or composition reaction.
And most of the combination reactions are exothermic reactions because there is formation of new bonds which gives out more heat.
For example:
1) Hydrogen gas combines with chlorine gas and forms hydrogen chloride gas as given below.
H2g + Cl2g → 2HClg
2) Silicon dioxide reacts with calcium oxide and forms calcium silicate.
SiO2s + CaOs → CaSiO3s
4) Differentiate reversible and irreversible reactions
Ans:
Reversible reaction:
- Reversible reaction will be reversed by using some conditions also.
- In this reaction, the forward and backward both reactions occurs simultaneously.
- Reversible reaction attains the equilibrium.
- And hence, reactants cannot be converted into products completely.
- Reversible reaction is a slow reaction.
Irreversible reaction:
- Irreversible reaction cannot be reversed.
- As it is a irreversible reaction it proceeds only in one direction and occurs only in forward direction.
- Due to which equilibrium is not attained in this reaction.
- And hence, reactants are converted into products completely.
- Irreversible reaction is the fast reaction.
VI.) Answer in detail
1) What are called thermolysis reactions?
Ans:
Thermal decomposition reaction or Thermolysis:
In this reaction, by applying the heat energy the decomposition of reactant molecule takes place.
As the reactant molecule is dissolved due to the absorption of heat, it is called as thermolysis.
For example:
1) HgO is decomposed into Hg and O2 by absorbing heat energy.
HgOs → 2Hgl + O2g
2) By heating calcium carbonate it decomposes to calcium oxide and carbon dioxide.
CaCO3s → CaOs + CO2g
2) Explain the types of double displacement reactions with examples.
Ans:
Double displacement reaction:
If in a reaction, two compounds react and their ions get interchanged then that reaction is called as double displacement reaction.
In this reaction, the ion of one compound will be replaced by the ion of another compound.
There are two types of double displacement reactions:
- Precipitation reaction
- Neutralization reaction
1) Precipitation reaction:
When aqueous solutions of two compounds are mixed they reacts and forms soluble compound and a insoluble compound ten that type of reaction is called as precipitation reaction.
For example:
When clear solution of potassium iodide and lead II nitrate mixed, potassium and lead displaces each other and a yellow precipitate of lead II iodide is formed.
Pb(NO3)2aq + 2KIaq → PbI2s ↓ + 2KNO3aq
2) Neutralization reaction:
When acid and base react with each other then salt water is formed this type of reaction is a double displacement reaction called as neutralization reaction.
For example:
When sodium hydroxide reacts with hydrochloric acid salt and water is formed.
In this reaction, sodium replaces hydrogen from hydrochloric acid and forms sodium chloride a neutral salt.
NaOHaq + HClaq → NaClaq + H2Ol
3) Explain the factors influencing the rate of a reaction
Ans:
The following factors affect the rate of reaction:
1) Nature of the reactants:
The reaction of sodium with hydrochloric acid is faster than that with acetic acid because, hydrochloric acid is stronger than acetic acid and hence more reactive.
Thus, the nature of reactants also influence the rate of reaction.
2) Concentration of the reactants:
Change in the amount of reactants also changes the rate of reaction.
More is the concentration more are the particles per unit volume and hence reaction occurs faster. Hence, granulated zinc reacts faster with 2M hydrochloric acid than 1M hydrochloric acid.
3) Temperature:
The rate of reaction increases as the temperature is increased because, when heat energy is provided to the reactant molecule then there will be more breaking of bonds happens which speeds up the reaction.
For example: at room temperature, calcium carbonate reacts with hydrochloric acid slowly.
But when this reaction mixture is heated the rate of reaction will be increased.
4) Pressure:
If the reactants are in the form of gas and if their pressure is increased then the reaction rate also increases.
Because, if pressure is increased the reacting molecules comes closer and collides.
5) Catalyst:
Catalyst increases the rate of reaction without taking part in the chemical reaction.
For example: on heating potassium chlorate, it decomposes to form potassium chloride and oxygen gas but at a slower rate.
When manganese dioxide is added it increases the rate of reaction.
6) Surface area of the reactants:
The solid in the form of powder reacts more readily.
For example: powdered calcium carbonate reacts more readily with hydrochloric acid than marble chips. Because, in powdered form of reactants the surface area increases and more energy is given to reactants molecules to collide.
And hence, the rate of reaction increases.
4) How does pH play an important role in everyday life?
Ans:
Importance of pH in everyday life:
- Our body works within the pH range 7.0 – 7.8 only. The different body fluids are having different values of pH. The pH of blood is in the range 7.35-7.45. If there is decrease or increase in blood pH it may cause the disease also.
- The ideal blood pH value is 7.4. In our stomach hydrochloric acid is produced which helps in digesting the food. During indigestion the stomach produces too much acid due to which we feel pain and irritation. The pH of stomach fluid is 2.0.
- The pH of saliva ranges in 6.5-7.5. When the pH of mouth saliva will less than 5.5 then enamel get weathered. Cleaning toothpastes are made basic to neutralize the excess acid and prevent tooth decay.
- In agriculture also, the pH of soil is more important.
5) What is a chemical equilibrium? What are its characteristics?
Ans:
Chemical equilibrium:
Chemical equilibrium is the state of reversible chemical reaction in which there is no change in the amount of reactants and products takes place.
Hence, at equilibrium
Rate of forward reaction = rate of backward reaction.
Characteristics of chemical equilibrium:
- In chemical equilibrium, the rate of both forward and backward reaction are same or equal.
- The observable properties like pressure, concentration, colour, density, viscosity etc. of the system are not changed throughout the reaction.
- The chemical equilibrium is the dynamic equilibrium.
- In case of physical equilibrium, the volume of all the phases will remains constant.
VII.) HOT questions
1) A solid compound ‘A’ decomposes on heating into ‘B’ and a gas ‘C’. On passing the gas ‘C’ through water, it becomes acidic. Identify A, B and C.
Ans:
Here, A is the calcium carbonate CaCO3 which on decommission on heating gives CaO and CO2 gas.
When again, CO2 is dissolved in water forms the carbonic acid.
CaCO3s → CaOs + CO2g
Calcium carbonate Calcium oxide
And CO2 + H2O → H2CO3 Carbonic acid
Thus, here A→ Calcium carbonate CaCO3
B→ Carbon dioxide CO2
C→ Carbonic acid H2CO3
2) Can a nickel spatula be used to stir copper sulphate solution? Justify your answer.
Ans:
A nickel spatula cannot be used to stir copper sulphate solution because, nickel will displaces the copper from copper sulphate solution and copper may get deposited on the nickel spatula.
Hence, a nickel spatula cannot be used to stir the copper sulphate solution.
VIII.) Solve the following problems
1) Lemon juice has a pH 2, what is the concentration of H+ ions?
Ans:
Given that, pH of lemon juice is 2.
Hence, concentration of H+ ions is given by,
[H+] = 10-pH
[H+] = 10-2
[H+] = 1* 10-2 M
Thus, the concentration of H+ ions in lemon juice of pH 2 is1* 10-2 M
2) Calculate the pH of 1.0 ×10–4 molar solution of HNO3.
Ans:
HNO3 gives H+ and NO3– ions.
Hence, HNO3 → H+ + NO3– ions
1*10-4 M 1*10-4 M
Thus, pH = -log [H+]
= -log [1*10-4]
= log [1*104]
= 4 log [10]
pH = 4 since, log [10] = 1
Thus, the pH of 1*10-4 M HNO3 solution is 4.
3) What is the pH of 1.0 × 10–5 molar solution of KOH?
Ans:
KOH gives K+ and OH– ions.
Hence, KOH → K+ + OH–
1*10-5 M 1*10-5 M
pOH = -log [OH-]
= -log [1*10-5]
= log [1*105]
= 5 log [10]since, log [10] = 1
pOH = 5
But, pH + pOH = 14
Hence, pH = 14 – pOH = 14 – 5 = 9
pH = 9
Thus, pH of 1*10-5 M solution of KOH is 9.
4) The hydroxide ion concentration of a solution is 1 × 10–11M. What is the pH of the solution?
Ans:
We know that, [H+] * [OH–] = 10-14
[H+] * 1*10-11 = 10-14
[H+] = 10-3
And pH = -log [H+]
= -log [10-3]
= 3 log [10]since, log [10] = 1
pH = 3
Thus, the pH of the solution is 3.
