Consider the interconversion of A molecules (red spheres) and B molecules (blue spheres) according to the reaction A ⇌ B. Each of the following series of pictures represents a separate experiment in which time increases from left to right:
- (a) Which of the experiments has resulted in an equilibrium state?
- (b) What is the value of the equilibrium constant Kc for the reaction A ⇌ B?
- (c) Explain why you calculate Kc without knowing the volume of the reaction vessel.
(a)
Interpretation:
From the given experiments, the one resulted in equilibrium state has to be identified.
Concept introduction:
Chemical equilibrium:
It is defined as a state in which concentrations of reactants and products are same over a period of time. An equilibrium mixture is a mixture in which reactants and products are in equilibrium.
Answer to Problem 13.26CP
Experiment one and three are in equilibrium state.
Explanation of Solution
Reason correct options:
Given,
Figure 1
In experiment one and three, the number of red spheres A and blue spheres B are same over a period of time. In both experiments third and fourth box have same number of A and B. Hence, experiment one and three are in equilibrium state.
Reason incorrect options:
In experiment two, the number of A and B are not same over a period of time. Hence, experiment two is not in equilibrium.
(b)
Interpretation:
The equilibrium constant for given reaction has to be calculated.
Concept introduction:
Equilibrium constant
Equilibrium constant
Consider the reaction where A reacts to give B.
On rearranging,
Where,
Answer to Problem 13.26CP
The value of equilibrium constant is
Explanation of Solution
Given,
The equilibrium constant is calculated by substituting concentrations of reactants and products in equilibrium constant expression.
Therefore, the value of equilibrium constant is
(c)
Interpretation:
The reason for calculating equilibrium constant without knowing volume of the reaction vessel has to be explained.
Concept introduction:
Equilibrium constant
Equilibrium constant
Consider the reaction where A reacts to give B.
On rearranging,
Where,
Explanation of Solution
At equilibrium the number of molecules on reactant and product side remains same and volume gets cancelled while substituting in equilibrium constant expression. Hence, equilibrium constant
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Chapter 13 Solutions
General Chemistry: Atoms First
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