Q: For the reaction $$N_2(g$$) + $$O_2(g$$) \rightleftharpoons 2NO(g)$$, if the vessel is charged with 0.200$ atm N_2$ and 0.800$ atm O_2$, and K_p = 1.5$$ \times $$10^{-10} at 25$$°C, what is the equilibrium partial pressure of $$NO$$?

$$P_{NO} = \sqrt{K_p \times P_{N_2$} \times P_{O_2$}}$$

Question 1

Which of the following correctly expresses the equilibrium constant $$K_c$$ for the reaction: $$2NOBr(g) \rightleftharpoons 2NO(g) + Br_2$(g) in $$terms of concentrations?

Accepted Answer

$$K_c = \dfrac{[NO]^2[Br_2$]}{[NOBr]^2}$$

Question 2

Given the reaction $$N_2(g$$) + $$O_2(g$$) ightleftharpoons 2NO(g)$$, and K_c = 1.5$$ 	imes $$10^{-10} at 25$$°C, what does the small value of $$K_c$$ indicate about the equilibrium mixture?

Accepted Answer

The mixture contains mostly reactants.

Question 3

For the reaction $$CCl_4(g$$) \rightleftharpoons C(s) + 2Cl_2(g)$$, K_p = 0.76$ at 700 K. Which of the following is the correct equilibrium constant expression in terms of partial pressures?

Accepted Answer

$$K_p = \dfrac{P_{Cl_2$}^2}{P_{$$CCl_4$$}}$$

Question 4

If the equilibrium constant $$K_c$$ for a reaction is $$2.5 	imes 10^3$, which statement is true about the equilibrium mixture?

Accepted Answer

Products dominate at equilibrium.

Question 5

What is the value of $$K_c$$ for the reverse of the reaction $$A + B \rightleftharpoons C if $$the forward reaction has $$K_c = 4.0$$?

Accepted Answer

$$K_c = 0.25$$

Question 6

Equilibrium is reached when the __________ no longer change.

Accepted Answer

concentrations of reactants and products

Question 7

If the pressure is increased at equilibrium for a reaction in a cylinder with a moveable piston, what will happen to the position of equilibrium for the reaction $$N_2(g) + 3H_2(g$$) \rightleftharpoons 2NH_3(g)$$?

Accepted Answer

It will shift toward the side with fewer moles of gas.

Question 8

A catalyst is added to a reaction at the beginning. What effect does this have on the equilibrium position and the rate at which equilibrium is reached?

Accepted Answer

It does not change the equilibrium position but increases the rate at which equilibrium is reached.

Question 9

For the reaction $$N_2(g$$) + $$O_2(g$$) ightleftharpoons 2NO(g)$$, if the vessel is charged with 0.200$ atm N_2$ and 0.800$ atm O_2$, and K_p = 1.5$$ 	imes $$10^{-10} at 25$$°C, what is the equilibrium partial pressure of $$NO$$?

Accepted Answer

$$P_{NO} = \sqrt{K_p 	imes P_{N_2$} 	imes P_{O_2$}}$$

Question 10

If heat is added to an exothermic reaction at equilibrium, what will happen to the concentration of products?

Accepted Answer

It will decrease.

Question 11

If $$NOBr is $$removed from the equilibrium mixture $$2NOBr(g) \rightleftharpoons 2NO(g) + Br_2$(g)$$, what will happen to the system?

Accepted Answer

The system will shift to produce more $$NOBr.$$

Question 12

At equilibrium, if $$K_c \u003c 1$$, which of the following is true?

Accepted Answer

Reactants dominate at equilibrium.

Question 13

The larger the magnitude of $$K_{sp}$$, the __________ soluble the ionic solid.

Accepted Answer

more

Question 14

What is the molar solubility of $$Ca(OH)_2 at 25$$°C if $$K_{sp} = 6.5 	imes 10$$^{-6}$$?

Accepted Answer

$$s = \sqrt[3]{K_{sp}/4}$$

Question 15

Calculate $$K_{sp}$$ for $$La(OH)_3 if $$the molar solubility of $$La^{3+} is$$ $$2.29 	imes 10$$^{-4}$$ M.

Accepted Answer

$$K_{sp} = [La$$^{3+}$$][OH^-]^3$$

Question 16

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

Accepted Answer

Adding a catalyst

Question 17

For the reaction $$A(g) + B(g) ightleftharpoons C(g)$$, if the initial pressures are $$P_A = 0.200$$ atm, $$P_B = 0.100$$ atm, and $$K_p = 1.14 	imes 10$$^{-3}$$, what is the equilibrium partial pressure of C$?

Accepted Answer

Question 18

If the reaction $$2NOBr(g) \rightleftharpoons 2NO(g) + Br_2$(g) is at $$equilibrium and more $$NOBr is $$added, what will happen?

Accepted Answer

The system will shift to produce more $$NO$$ and $$Br_2.$$

Question 19

Which of the following best describes the effect of removing heat from an endothermic reaction at equilibrium?

Accepted Answer

The equilibrium shifts toward the reactants.

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