CHE 105/110 Introduction to Chemistry - Exercises and Answers

1.

What is the relationship between the K_sp expressions for a chemical reaction and its reverse chemical reaction?

1.

They are reciprocals of each other.

3.

For the equilibrium

$${\text{PCl}}_{\text{3}}{\text{(g) + Cl}}_{\text{2}}\text{(g)}\rightleftarrows {\text{PCl}}_{\text{5}}\text{(g) + 60 kJ}$$

list four stresses that serve to increase the amount of PCl₅.

3.

increase the pressure; decrease the temperature; add PCl₃; add Cl₂; remove PCl₅

5.

Does a very large K_eq favor the reactants or the products? Explain your answer.

5.

favor products because the numerator of the ratio for the K_eq is larger than the denominator

7.

Show that K_a × K_b = K_w by determining the expressions for these two reactions and multiplying them together.

$$\text{HX(aq)}\rightleftarrows {\text{H}}^{\text{+}}{\text{(aq) + X}}^{\text{–}}\text{(aq)}$$ $${\text{X}}^{\text{–}}{\text{(aq) + H}}_{\text{2}}\text{O(}\ell \text{)}\rightleftarrows {\text{HX(aq) + OH}}^{\text{–}}\text{(aq)}$$

7.

$K_{\text{a}}\times K_{\text{b}}=\frac{{\text{[H}}^{\text{+}}\text{]}{\text{[X}}^{\text{–}}\text{]}}{}$$\frac{\text{[HX]}}{}$$\frac{}{}\times \frac{\text{[HX]}}{}$$\frac{{\text{[OH}}^{\text{–}}\text{]}}{{\text{[X}}^{\text{–}}\text{]}}$$\frac{}{}={\text{[H}}^{\text{+}}{\text{][OH}}^{\text{–}}\text{]}=K_{\text{w}}$

9.

What is the solubility in moles per liter of AgCl? Use data from

Table 11.2 "Solubility Product Constants for Slightly Soluble Ionic Compounds".

9.

1.3 × 10⁻⁵ mol/L

11.

Under what conditions is K_eq = K_P?

11.

K_eq = K_P when the number of moles of gas on both sides of the reaction is the same.

13.

What is the pH of a saturated solution of Mg(OH)₂? Use data from

Table 11.2 "Solubility Product Constants for Slightly Soluble Ionic Compounds".

13.

10.35

15.

For a salt that has the general formula MX, an ICE chart shows that the K_sp is equal to x², where x is the concentration of the cation. What is the appropriate formula for the K_sp of a salt that has a general formula of MX₂?

15.

4x³

17.

17.

1. 2.66 × 10⁻⁵ M
2. 9.41 × 10⁻¹⁵