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 Co, from the air and turns back into hard, durable

limestone.

Suppose a limekiln of volume 450. L is pressurized with carbon dioxide gas to 8.03 atm, and heated to 1000. °C. When the amount of CO, has stopped

changing, it is found that 1.29 kg of CaCO3 have appeared.

Calculate the pressure equilibrium constant K, this experiment suggests for the equilibrium between CaCO, and Cao at 1000. °C. Round your answer to 2

significant digits.

Note for advanced students: it's possible there was some error in this experiment, and the value it suggests for K, does not match the accepted value.