Q: For the reaction $$2A(g) + B(g) \rightleftharpoons 2C(g)$$, the equilibrium constant $$K_p is $$related to $$K_c by $$which of the following equations?

$$K_p = K_c \times (RT$$)^{\Delta n}$$

Q: Given the following mechanism: Step 1: $$A \rightleftharpoons B$$ ($$K_1) $$Step 2: $$B \rightleftharpoons C$$ ($$K_2) $$Step 3: $$C \rightleftharpoons D$$ ($$K_3) $$What is the overall equilibrium constant $$K_{overall}$$ for the reaction $$A \rightleftharpoons D$$?

$$K_{overall} = K_1$ \times K_2$ \times K_3$

Question 1

Which of the following best describes a system at dynamic equilibrium?

Accepted Answer

The forward and reverse reaction rates are equal, and the concentrations of reactants and products remain constant over time.

Question 2

For the reaction $$aA + bB \rightleftharpoons cC + dD$$, the equilibrium constant expression $$K_c is$$:

Accepted Answer

$$K_c = \frac{[C]^c [D]^d}{[A]^a [B]^b}$$

Question 3

A reaction mixture initially contains only reactants. After some time, the reaction quotient $$Q_c is $$calculated and found to be less than $$K_c. $$What does this indicate about the direction the reaction will proceed?

Accepted Answer

The reaction will proceed in the forward direction to form more products.

Question 4

Which of the following statements about the equilibrium constant $$K is $$correct?

Accepted Answer

A large $$K$$ value indicates that the reaction favors the formation of products at equilibrium.

Question 5

For the reaction $$2A(g) + B(g) \rightleftharpoons 2C(g)$$, the equilibrium constant $$K_p is $$related to $$K_c by $$which of the following equations?

Accepted Answer

$$K_p = K_c 	imes (RT$$)^{\Delta n}$$

Question 6

A chemical system at equilibrium is disturbed by increasing the concentration of a reactant. According to Le Chatelier's Principle, what will happen?

Accepted Answer

The system will shift to produce more products.

Question 7

Consider the reaction $$N_2(g) + 3H_2(g$$) \rightleftharpoons 2NH_3(g)$$. If the total pressure is increased by decreasing the volume, what is the effect on the position of equilibrium?

Accepted Answer

The equilibrium shifts toward the side with fewer moles of gas.

Question 8

Which of the following is NOT included in the equilibrium constant expression for the reaction $$CaCO_3(s$$) \rightleftharpoons CaO(s) + $$CO_2(g$$)$$?

Accepted Answer

$$[$$CaCO_3$$]$$

Question 9

Given the following mechanism:
Step 1: $$A \rightleftharpoons B$$ ($$K_1)
$$Step 2: $$B \rightleftharpoons C$$ ($$K_2)
$$Step 3: $$C \rightleftharpoons D$$ ($$K_3)
$$What is the overall equilibrium constant $$K_{overall}$$ for the reaction $$A \rightleftharpoons D$$?

Accepted Answer

$$K_{overall} = K_1$ 	imes K_2$ 	imes K_3$

Question 10

A reaction has a very small $$K_c$$ value ($$K_c \ll 1). $$Which of the following is true about the equilibrium mixture?

Accepted Answer

The mixture contains mostly reactants.

Question 11

The Van't Hoff equation relates the change in the equilibrium constant $$K to $$which of the following variables?

Accepted Answer

Change in temperature

Question 12

For the reaction $$2SO_2(g) + O_2$(g) \rightleftharpoons 2SO_3(g)$$, the equilibrium concentrations are $$[SO_2$] = 0.20 M$$, $$[O_2$] = 0.10 M$$, and $$[SO_3$] = 0.40 M. $$What is the value of $$K_c$$?

Accepted Answer

$$K_c = \frac{[SO_3$]^2}{[SO_2$]^2 [O_2$]} = \frac{(0.40)^2$}{(0.20)^2$ 	imes 0.10} = 40$$

Question 13

A student is solving for the equilibrium concentration of $$A in $$the reaction $$A ightleftharpoons B$$ with $$K_c = 1.0 	imes 10$$^{-5}$$ and initial $$[A] = 0.10$$ M, $$[B] = 0$$ M. Which assumption can simplify the calculation?

Accepted Answer

Assume that the change in $$[A] is $$negligible compared to its initial concentration.

Question 14

Which of the following changes will NOT affect the value of the equilibrium constant $$K$$ for a given reaction?

Accepted Answer

Adding a catalyst

Question 15

A reaction mixture at equilibrium is heated. The reaction is exothermic. What will happen to the value of $$K$$?

Accepted Answer

$$K$$ will decrease.

Question 16

In a real-world scenario, the synthesis of ammonia ($$N_2 + 3H_2$$ \rightleftharpoons 2NH_3$$) is performed at high pressure. Why is high pressure used?

Accepted Answer

High pressure shifts the equilibrium toward the side with fewer moles of gas, increasing ammonia yield.

Question 17

For the reaction $$2NO_2(g) \rightleftharpoons N_2O_4(g)$$, an increase in temperature causes the color of the mixture to become darker brown. What can you conclude about the reaction?

Accepted Answer

The reverse reaction is endothermic, and increasing temperature favors the formation of $$NO_2 ($$brown gas).

Question 18

A reaction table (ICE table) is used to solve equilibrium problems. What does the 'C' row represent?

Accepted Answer

The change in concentrations as the system moves toward equilibrium.

Question 19

Which of the following is a correct statement about the reaction quotient $$Q$$?

Accepted Answer

$$Q is $$calculated using the same expression as $$K$$, but with current (not necessarily equilibrium) concentrations.

Chemical Equilibrium: Concepts, Calculations, and Applications

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