Question

1.         Write equilibrium (mass action) expressions for each of the following reactions:

(a) H₂(g) + I₂(g)          2 HI

(b)2 NO(g) + O₂(g)           2 NO₂(g)

(c)N₂(g) + 3 H₂(g)           2 NH₃(g)

(d) CO(g) + NO₂(g)           CO₂(g) + NO(g)

(e) 2 CO(g) + O₂(g)             2 CO₂(g)

2.    Write equilibrium expressions for each of the following equilibria:

(a) 2 C(s) + O₂(g)                  CO(g)

(b) Zn²⁺(aq) + H₂S(g)               ZnS(s) + 2 H⁺(aq)

(c) HCl(g) + H₂O()                  H₃O⁺(aq) + Cl^–(aq)

(d)H₂(g) +  O₂(g)                   H₂O(g)

3.         Which of the following is more likely to precipitate the hydroxide ion?

(a) Cu(OH)₂(s)            Cu²⁺(aq) + 2 OH^–(aq)                              K= 1.6 ´10^–20

(b)Ca(OH)₂(s)              Ca²⁺(aq) + 2 OH^–(aq)                             K= 7.9 ´10^–6

4.         The reaction, 3 H₂(g) + N₂(g)            2 NH₃(g), has the following equilibrium constants at the temperatures given:

                                               atT= 25°C, K= 2.8 ´10⁴

                                             at T= 500°C, K= 2.4 ´10^–7

(a) At which temperature are reactants favored?

(b)At which temperature are products favored?

5.         Consider the following equilibria involving SO₂(g) and their corresponding equilibrium constants:

SO₂(g) +  O₂(g) SO₃(g)         K₁

2 SO₃(g) 2 SO₂(g) + O₂(g)        K₂

Which of the following expressions relates K₁to K₂?

(a)K₂= K₁²

(b) K₂²= K₁

(c)K₂= K₁

(d)K₂= 1/K₁

(e) K₂= 1/K₁²

6.         The following data were collected for the reaction, H₂(g) + I₂(g)           2 HI(g), at equilibrium at 25°C.

            [H₂] = 0.10 mol L^–1, [I₂] = 0.20 mol L^–1, [HI] = 4.0 mol L^–1

            Calculate the equilibrium constant for the reaction at this temperature.

  

7.         The equilibrium constant for the reaction, 3 H₂(g) + N₂(g)                2 NH₃(g), at a given temperature is 1.4 ´10^–7. Calculate the equilibrium concentration of ammonia, if [H₂] = 1.2 ´10^–2mol L^–1and [N₂] = 3.2 ´10^–3mol L^–1.

8.         Hydrogen gas and iodine gas react via the following equation:

H₂(g) + I₂(g)             2 HI(g)                   K_c= 76 (at 600 K)

If 0.050 mol HI is placed in an empty 1.0-L flask at 600 K, what are the equilibrium concentrations of HI, I₂, and H₂?

9.         The equilibrium constant of the reaction of Cl₂(g) with PCl₃(g) to produce PCl₅(g) is 51 at a particular temperature. If the initial concentration of PCl₃is 0.012 mol L^–1 and the initial concentration of Cl₂is 0.125 mol L^–1, what are the equilibrium concentrations of all species?

10.        At a particular temperature, the equilibrium constant, K, for the dissociation of N₂O₄into NO₂is 133. If the initial concentration of N₂O₄is 0.100 mol L^–1, what are the concentrations of all species at equilibrium?

                                                  N₂O₄               2 NO₂

Answer 1

Answer 1

Answer 2 and 3

Answer 4

When Kc is more than 1 then products are favored at equilibrium.

a) At 500 ^o C, K_c is less than 1, so reactants are favored.

b) At 25 ^oC, K_c is more than 1, so products are favored.