Limestone stalactites and stalagmites are formed in caves by the following reaction: Ca2+ (aq) + 2HCO3 - CaCO3 (s) + CO2 (g) + H2O (g) (continued in description)

Question

If one mole of calcium carbonate forms at 298K under one atmosphere pressure, the reaction performs

3.45 kJ of PV work, pushing back at the atmosphere as the gaseous carbon dioxide forms. At the

same time, 33.45 kJ of heat is absorbed from the environment as the calcium carbonate solidifies.

what are the values of H and E for this reaction?

Answer 1

∆H = +33.45kJ (positive because heat is absorbed by the system from the surroundings)

∆E = q + w

q = +33.45 kJ

w = -3.45 kJ (negative because the system is doing work on the surroundings)

∆E = 33.45 + (-3.45)

∆E = +30 kJ