So calculate the H for the other two reactions a room temperature and combine the reactions to calculate the H of the decomposition of calcium carbonate using the Hess's Law
As with the properties of a substance, the changes that substances undergo can be classified as either physical or chemical. During physical changes a substance changes its physical appearance, but not its composition. The evaporation of water is a physical change.
(I searched that up but here’s an explanation with my own words that you can use):
Change in matter can be classified as a physical change as well as a chemical change due to the properties of substance. A physical change changes substance within its appearance but not its composition. For an example: The evaporation of water is a physical change.
There you go hopefully that helped
M = n x Mr
Mr of H20 - 18.006
M = 1.15mol x 18.006g/mol
= 20.7069g
= 20.7g (3sfg)