Question

When limestone (solid CaCO3) is heated, it decomposes into lime (solid CaO) and carbon dioxide gas. This is an extremely useful industrial process of great antiquity, because powdered lime mixed with water is the basis for mortar and concrete — the lime absorbs CO2 from the air and turns back into hard, durable limestone.

Suppose some calcium carbonate is sealed into a limekiln of volume 750.L and heated to 770.0°C

When the amount of CaCO3 has stopped changing, it is found that 8.77kg have disappeared.

Calculate the pressure equilibrium constant Kp this experiment suggests for the equilibrium between CaCO3 and CaO at 770.0°C Round your answer to 2 significant digits.

Answer 1

Given T = 770.0'c = (770.0 + 273.15) K = 1043:15 K. V = 750. L Now from the chemical equation- CaCO₃ (6) GO (s) + CO₂(g) or 7 I mol GCO3 → 1 moi CO₂ 100. g CaCO3 → 1 mol CO₂ 8.77 x 103 g Cacos → *8.77 xlo mol 100. = 87.7 mol CO2 Finally CaCO₃ (s) Ź Cao (s) + CO₂ (g) Kp = Pco, = nRT (using pV = nRT) 87.7 mol x - = Oy x 1043.15K Kp 0.0821 L atm K.mol 750. L So, Kp = 10.