Please help me with honors chem

Question

Identify the following chemical reaction as exothermic or endothermic: CaCO3 + 178 kJ --> CaO + CO2

A. Endothermic

B. Exothermic    

Answer 1

In a chemical equation, if heat is written on the reactant side, then the reaction is endothermic. If it is on the product side, then the reaction is exothermic. In this reaction, the decomposition of CaCO₃ is endothermic since heat is needed to break down the compound into 2 simpler compounds.