07 Chemical Equilibrium Quiz | Chemistry Quiz
In this Chemistry quiz article we are going to share some Chemistry study material and some multiple-choice questions of solution chapter which having some topics like Equilibrium state, Law of mass action, Law of equilibrium and Equilibrium constant, Kp & Kc Relationship and Characteristics of K, Activation energy, Standard free energy and Degree of dissociation and Vapour density and Le-Chaterlier principle and It’s application ..
Whenever we hear the word Equilibrium immediately a picture arises in our mind an object under the influence of two opposing forces. For chemical reactions also this is true. A reaction also can exist in a state of equilibrium balancing forward and backward reactions.
Reversible and Irreversible reactions
A chemical reaction is said to have taken place when the concentration of reactants decreases, and the concentration of the products increases with time. The chemical reactions are classified on the basis of the extent to which they proceed, into the following two classes;(1) Reversible reactions : Reaction in which entire amount of the reactants is not converted into products is termed as reversible reaction.
(i) Characteristics of reversible reactions
(a) These reactions can be started from either side,
(b) These reactions are never complete,
(c) These reactions have a tendency to attain a state of equilibrium, in which Free energy change is zero.
Equilibrium state Quiz
1. Which of the following conditions represents an equilibrium(a) Freezing of ice in an open vessel, the temperature of ice is constant
(b) Few drops of water are present along with the air in a balloon, the temperature of a balloon is constant
(c) Water is boiling in an open vessel over the stove, the temperature of the water is constant
(d) All the statements (a), (b) and (c) are correct for the equilibrium
SOL: (c) In a reversible reaction some amount of the reactants remain unconverted into products.
2. When rate of forward reaction becomes equal to backward reaction, this state is termed as
(a) Chemical equilibrium (b) Reversible state
(c) Equilibrium (d) All of these
SOL: (d) In lime klin CO2 escaping regularly so reaction proceeds in forward direction.
4. In chemical reaction A⇌B, the system will be known in equilibrium when
(a) A completely changes to B
(b) 50% of A changes to B
(c) The rate of change of A to B and B to A on both the sides are same
(d) Only 10% of A changes to B
SOL: B
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5. A chemical reaction is at equilibrium when
(a) Reactants are completely transformed into products
(b) The rates of forward and backward reactions are equal
(c) Formation of products is minimised
(d) Equal amounts of reactants and products are present
SOL: A
Law of mass action Quiz
6. Under a given set of experimental conditions, with increase in the concentration of the reactants, the rate of a chemical reaction
(a) Decreases
(b) Increases
(c) Remains unaltered
(d) First decreases and then increases
SOL: B
7. The law of mass action was enunciated by
(a) Guldberg and Waage
(b) Bodenstein
(c) Birthelot
(d) Graham
SOL: A
8. Theory of ‘active mass’ indicates that the rate of chemical reaction is directly proportional to the
(a) Equilibrium constant
(b) Properties of reactants
(c) Volume of apparatus
(d) Concentration of reactants
SOL: A
9. The rate at which substances react depends on their
(a) Atomic weight
(b) Molecular weight
(c) Equivalent weight
(d) Active mass
SOL: D
10. Which is false
(a) The greater the concentration of the substances involved in a reaction, the lower the speed of the reaction
(b) The point of dynamic equilibrium is reached when the reaction rate in one direction just balances the reaction rate in the opposite direction
(c) The dissociation of weak electrolyte is a reversible reaction
(d) The presence of free ions facilitates chemical changes
SOL: (a) As we increase the concentration of substance, then speed of the reaction increases.
Law of equilibrium and Equilibrium constant Quiz
11. 4 moles of A are mixed with 4 moles of B. At equilibrium for the reaction A+B⇌C+D, 2 moles of C and D are formed. The equilibrium constant for the reaction will be
(a) 1/4 (b) 1/2
(c) 1 (d) 4
SOL: (c)
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12. A reversible chemical reaction having two reactants in equilibrium. If the concentrations of the reactants are doubled, then the equilibrium constant will
(a) Also be doubled (b) Be halved
(c) Become one-fourth (d) Remain the same
SOL: (d) K is a characteristic constant for the given reaction.
13. The equilibrium constant in a reversible reaction at a given temperature
(a) Depends on the initial concentration of the reactants
(b) Depends on the concentration of the products at equilibrium
(c) Does not depend on the initial concentrations
(d) It is not characteristic of the reaction
SOL: (c) Equilibrium constant is independent of original concentration of reactant.
14. In a chemical equilibrium A+B ⇌ C+D, when one mole each of the two reactants are mixed, 0.6 mole each of the products are formed. The equilibrium constant calculated is
(a) 1 (b) 0.36
(c) 2.25 (d) 4/9
SOL: (c) A+ B ⇌C+ D Initial
1 1 0 0
Activation energy, Standard free energy and Degree of dissociation and Vapour density
15. A reaction attains equilibrium when the free energy change accompanying it is
(a) Positive and large
(b) Zero
(c) Negative and large
(d) Negative and small
SOL: B
16. In a reversible reaction, the catalyst ¬¬
(a) Increases the activation energy of the backward reaction
(b) Increases the activation energy of the forward reaction
(c) Decreases the activation energy of both, forward and backward reaction
(d) Decreases the activation energy of forward reaction
SOL: (c) Decreases the activation energy of both forward and backward reaction.
Le-Chaterlier principle and It’s application Quiz
17. The reactionA+B⇌C+D heat has reached equilibrium. The reaction may be made to proceed forward by
(a) Adding more C
(b) Adding more D
(c) Decreasing the temperature
(d) Increasing the temperature
SOL: (c) Exothermic reaction is favoured by low temperature to proceed in forward direction.
18. On the velocity in a reversible reaction, the correct explanation of the effect of catalyst is
(a) It provides a new reaction path of low activation energy
(b) It increases the kinetic energy of reacting molecules
(c) It displaces the equilibrium state on right side
(d) It decreases the velocity of backward reaction
SOL: (a) Effect of catalyst is that it attains equilibrium quickly by providing a new reaction path of low activation energy. It does not alter the state of equilibrium.
19. Select the correct statement from the following
(a) Equilibrium constant changes with addition of catalyst
(b) Catalyst increases the rate of forward reaction
(c) The ratio of mixture at equilibrium is not changed by catalyst
(d) Catalyst are active only in solution
SOL:C
20. According to Le-chatelier principle, if heat is given to solid-liquid system, then
(a) Quantity of solid will reduce
(b) Quantity of liquid will reduce
(c) Increase in temperature
(d) Decrease in temperature
SOL: (a) On increasing temperature equilibrium will shift in forward direction due to decrease in intermolecular forces of solid.
21. Which of the following factors will favour the reverse reaction in a chemical equilibrium
(a) Increase in the concentration of one of the reactants
(b) Removal of at least one of the product at regular time intervals
(c) Increase in the concentration of one or more products
(d) None of these
SOL: (c) A reaction is in equilibrium it will shift in reverse or backward direction when we increase the concentration of one or more product (from Le chatelier’s principle).
22. In the formation of SO2 by contact process, the conditions used are
(a) Catalyst, optimum temperature and higher concentration of reactants
(b) Catalyst, optimum temperature and lower concentration of reactants
(c) Catalyst, high temperature and higher concentration of reactants
(d) Catalyst, low temperature and lower concentration of reactants
SOL: (a) According to Le chatelier’s principle.
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23. In the reaction A(g)+B(g) ⇌ C(g), the backward reaction is favoured by
(a) Decrease of pressure
(b) Increase of pressure
(c) Either of the two
(d) None of the two
SOL: A
24. Which of the following conditions is favourable for the production of ammonia by Haber's process
(a) High concentration of reactants
(b) Low temperature and high pressure
(c) Continuous removal of ammonia
(d) All of these
SOL: D
25. According to Le-chatelier's principle, which of the following factors influence a chemical system
(a) Concentration only
(b) Pressure only
(c) Temperature only
(d) Concentration, pressure and temperature
SOL: D
26. Which of the following will favour the reverse reaction in a chemical equilibrium
(a) Increasing the concentration of the reactants
(b) Removal of at least one of the products at regular intervals
(c) Increasing the concentration of one or more of the products
(d) Increasing the pressure
SOL: B
