Q: Which of the following is true for the autoionization of water at 25°C?

$$[\mathrm{H}_3\mathrm{O}^+] = [\mathrm{OH}^-] = 1.00 \times 10$$^{-7}$$ M

Q: For a weak acid $$HA$$ with $$K_a = 1.8 \times 10$$^{-5}$$, what is the K_b$ for its conjugate base?

$$K_b = \dfrac{1.0 \times 10$$^{-14}$$}{1.8 \times 10$$^{-5}$$}$$

Question 1

Which of the following best describes what happens to the equilibrium position of the reaction $$\mathrm{Hb} + \mathrm{O}_2 \rightleftharpoons \mathrm{HbO}_2$$ when the concentration of $$\mathrm{O}_2$$ increases in the lungs?

Accepted Answer

The equilibrium shifts to the right, producing more $$\mathrm{HbO}_2.$$

Question 2

For the reaction $$\mathrm{N}_2(g) + \mathrm{O}_2(g) \rightleftharpoons 2\mathrm{NO}(g)$$, the equilibrium constant $$K is $$very small. What does this imply about the concentrations of reactants and products at equilibrium?

Accepted Answer

There will be much more $$\mathrm{N}_2$$ and $$\mathrm{O}_2$$ than $$\mathrm{NO} at $$equilibrium.

Question 3

Which of the following changes will NOT affect the position of equilibrium for the reaction $$\mathrm{CaCO}_3(s) \rightleftharpoons \mathrm{CaO}(s) + \mathrm{CO}_2(g)$$?

Accepted Answer

Adding more $$\mathrm{CaCO}_3(s).$$

Question 4

Given the reaction $$2\mathrm{SO}_2(g) + \mathrm{O}_2(g) ightleftharpoons 2\mathrm{SO}_3(g)$$ with $$K_c = 8 	imes 10$$^{25}$$ at 27°C, what does this value of K_c$ indicate?

Accepted Answer

The reaction favors the products at equilibrium.

Question 5

Which of the following is the correct equilibrium constant expression for the reaction $$2\mathrm{N}_2\mathrm{O}_5(g) \rightleftharpoons 4\mathrm{NO}_2(g) + \mathrm{O}_2(g)$$?

Accepted Answer

$$K = \dfrac{[\mathrm{NO}_2]^4[\mathrm{O}_2]}{[\mathrm{N}_2\mathrm{O}_5]^2}$$

Question 6

If the equilibrium constant for a reaction is $$K$$, what is the equilibrium constant for the reverse reaction?

Accepted Answer

$$\dfrac{1}{K}$$

Question 7

A reaction mixture has $$Q \u003c K. $$What will happen as the system moves toward equilibrium?

Accepted Answer

The reaction will proceed in the forward direction, increasing product concentrations.

Question 8

Which of the following statements about Le Chatelier’s Principle is correct?

Accepted Answer

If a product is removed from a system at equilibrium, the equilibrium shifts to produce more products.

Question 9

Which of the following is true for the autoionization of water at 25°C?

Accepted Answer

$$[\mathrm{H}_3\mathrm{O}^+] = [\mathrm{OH}^-] = 1.00 	imes 10$$^{-7}$$ M

Question 10

Which of the following acids is expected to be the strongest based on the number of oxygens and the electronegativity of the central atom?

Accepted Answer

$$HClO_3$$

Question 11

A solution has $$[\mathrm{H}_3\mathrm{O}^+] = 2.0 	imes 10$$^{-5}$$ M. What is the pH of the solution?

Accepted Answer

pH = 4.70

Question 12

Which of the following salts will produce a basic solution when dissolved in water?

Accepted Answer

NaF

Question 13

Which of the following is a Lewis acid?

Accepted Answer

$$BF_3$$

Question 14

Which of the following statements is true about strong acids?

Accepted Answer

They ionize completely in water.

Question 15

For a weak acid $$HA$$ with $$K_a = 1.8 	imes 10$$^{-5}$$, what is the K_b$ for its conjugate base?

Accepted Answer

$$K_b = \dfrac{1.0 	imes 10$$^{-14}$$}{1.8 	imes 10$$^{-5}$$}$$

Question 16

Which of the following best explains why the percent ionization of a weak acid decreases as its initial concentration increases?

Accepted Answer

The increase in $$[H_3O^+] is $$less than the increase in $$[HA]_{init}$$ due to Le Chatelier’s Principle.

Question 17

Which of the following is the correct relationship between $$K_p$$ and $$K_c$$ for the reaction $$aA(g) + bB(g) \rightleftharpoons cC(g) + dD(g)$$?

Accepted Answer

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

Question 18

A 0.10 M solution of $$\mathrm{Ca(OH)_2} is $$prepared. What is the pH of the solution?

Accepted Answer

pH = 13.30

Question 19

Which of the following best describes the effect of decreasing the volume of a container on the equilibrium position of a reaction involving gases?

Accepted Answer

The equilibrium shifts toward the side with fewer gas molecules.

Chemical Equilibrium and Acid-Base Chemistry: Exam 3 Study Guide

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