• concentrations of pure solids
• concentrations of pure liquids (in heterogeneous equilibria),
• solvents (in homogeneous equilibria

Sample Problems:

1. Consider the following heterogeneous equilibrium:

CaCO_{3 (s)} ←→CaO _(s) + CO_{2 (g)}

At 800 ^oC, the pressure of CO₂ is 0.236 atm. Calculate (a) K_c and (b) K_p for the reaction at this temperature.

2. Consider the following equilibrium at 395 K:

NH₄HS _(s) ←→NH_{3 (g)} + H₂S_(g)

The partial pressure of each gas is 0.265 atm. Calculate (a) K_c and (b) K_p for the reaction

3. The equilibrium constant Kp for the reaction

PCl5 _(g) ←→PCl_{3 (g)} + Cl_2(g)

is found to be 1.05 at 250 ^oC. If the equilibrium partial pressures of PCl₅ and PCl₃ are 0.875 atm and 0.463 atm, respectively, what is the equilibrium partial pressure of Cl₂ at this temperature?

4. The equilibrium constant Kp for the reaction

2 NO_{2 (g)} ←→2 NO _(g) + O_2(g)

is 158 at 1000 K. Calculate P_O2 if P_NO2 = 0.400 atm and P_NO = 0.270 atm.

Labels: Chemical Equilibrium, Chemistry Lecture, Sample Problems