Consider a reaction, A2 (g) + B2 (g) β 2AB (g), that has reached equilibrium. Which statement is TRUE at equilibrium?
A. The total concentrations of A2 and B2, and the concentration of AB are equal.
B. The reaction stops for both directions since it has reached equilibrium.
C. There are more products present than reactants.
D. The rate constants of the forward and reverse reactions are equal.
E. The rates of the forward and reverse reactions are equal.
2. Consider a reaction, A2 (g) + B2 (g) β 2AB (g), that is at equilibrium at room temperature. If the equilibrium constant K is 2.4 Γ 10^47, what does the magnitude of the equilibrium constant tell us about the reaction?
A. At equilibrium, the reaction is very fast since the equilibrium constant is very large.
B. At equilibrium, the concentration of products will be much greater than that of the reactants.
C. At equilibrium, the concentration of the products will be equal to that of the reactants.
D. The forward reaction is favored and the forward reaction proceeds to essentially completion.
E. Both B and D are correct.
3. For a generic chemical reaction, aA(g) + B(g) β cC(g) + dD(g), where a, b, c, and d are chemical coefficients. Note that A and B represent reactants while C and D are products. The equilibrium constant (K) can be expressed as below.
Kc = (C)^c(D)^d / (A)^a(B)^b
and
Kp = (PC)^c(PD)^d / (PA)^a(PB)^b
Write down the expression for the equilibrium constant in terms of concentration and pressure, respectively.
(1) 2SO2 (g) + O2 (g) β 2SO3 (g)
Kc = [SO3]^2 / [SO2]^2[O2]
Kp = (PSO3)^2 / (PSO2)^2(PO2)
(2) 2 NH4HS(s) β NH3(g) + H2S(g)
Kc = [NH3][H2S] / [NH4HS]^2
Kp = (PNH3)(PH2S) / (PNH4HS)^2
(3) PCl3(s) + Cl2(g) β PCl5(s)
Kc = [PCl5] / [PCl3][Cl2]
Kp = (PPCl5) / (PPCl3)(PCl2)
4. The relationship of Kc and Kp:
(1) Derive the relationship of Kc and Kp for a generic reaction, aA(g) + bB(g) β cC(g) + dD(g).
Kp = Kc(RT)^(Ξn)
where Ξn = (c + d) - (a + b)
(2) In which of the following reactions will Kc = Kp?
I. 4HCl(g) + O2(g) β 2Cl2(g) + 2H2O(l)
II. SO3(g) + NO(g) β SO2(g) + NO2(g)
III. Fe2O3(s) + 3 CO(g) β 2 Fe(s) + 3CO2(g)
IV. 2 NO(g) + O2(g) β 2 NO2(g)
A. I, II, and III only
B. II only
C. II and III only
D. I and IV
E. III only
(3) Nitrogen monoxide, a pollutant in automobile exhaust, is oxidized to nitrogen dioxide in the atmosphere according to the equation shown here. Find Kc for this reaction.
2NO(g) + O2(g) β 2NO2(g)
Kp = 2.2 Γ 10^12 at 25Β°C