Answer: Synthesis/ Combination
reaction
4 Al + 3S2 => 2 Al2S3
Explanation: The equation is now balanced the amount of each individual atom in both the reactant and product sides are equal.
The molar mass of Fe would be 55.8450.
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