If the following reaction is carried out with 30.0 g of CaCO3 and excess HCl, what is the maximum mass of CaCl2 that can be produced?

answer is: c. the experiment shows that the red substance experienced a chemical change.

this is chemical change (chemical reaction), because two new substances are formed (metalig liquid and gas), the atoms are rearranged and the reaction is followed by an energy change.

this is example of chemical decomposition.

chemical decomposition (analysis) is the separation of a single chemical compound into its two or more elemental parts or to simpler compounds.  

chemical decomposition is opposite of chemical synthesis.

the complete reaction for the formation of aluminum oxide is as follows;

4al + 3 > 2

so if the molar mass of the is 32.0 g/mol and

so, to form 3.80 mol of

(3.80 mol ) x (3 mol ) x (32.0 g )

dividing by 2 because two moles of will be formed;

∴ 364.8/2   = 182.4g