Chapter 14: Equilibrium

Question 1

explain what the magnitude or size of a reaction’s equilibrium constant tells us about the relative amounts of reactant and product at equilibrium

Answer 1

if K is large (K>1), the products predominate at equilibrium. if K is small (K<1), the reactants predominate at equilibrium. If K is approximately 1, then roughly equal amounts of reactants and products are present, with one only slightly favored over the other

Question 2

When a system has reached equilibrium, have all chemical reactions stopped? explain

Answer 2

reactants still take place at equilibrium. however the rates of the forward and reverse reactions are equal so concentration remain constant over time

Question 3

write the equation of the equilibrium constant, K, of the following reactions:
- N2(g) + 3 H2(g) -> 2 NH3(g)
- CaCO3(s) -> CaO(s) + CO2 (g)
- FeSCN^+2(aq) -> Fe^+3(aq) + SCN^-(aq)
- Cr2O7^-2(aq) + H2O(l) -> 2 CrO4^-2(aq) + 2 H^+ (aq)

Answer 3

K = [NH3]2/[N2][H2]3
K = [CO2]
K = [Fe^3+][SCN^-]/[FeSCN^2+]
K = [CrO4^2-]2[H+]2/[Cr2O7^2-]

Question 4

For the reaction N2(g) + 3 Cl2(g) -> 2 NCl3(g) an analysis of the mixture at equilibrium showed that the concentrations were [N2(g)] = 1.4x10^-3 M, [Cl2(g)] = 4.3x10^-4 M, and [NCl3(g)] = 2.80x10^-4 M. what is the reaction’s equilibrium constant?

Answer 4

k = [NCl3]2/[N2][Cl2]3
K = [2.8]/[1.4][4.3]3
K = 7.04x10^5

Question 5

do the following reaction favor reactants or products at equilibrium?
1) CaCO3 -> CaO + CO K=1.9
2) CO + C2 -> COC2 K=1.2

Answer 5

1) reactants
2) products