Exothermic & Endothermic

1.
Each substance in known amount contains a certain amount chemical energy (or said to be energy content).
Case 1: If the total amount of chemical energy stored in the reactants is greater than that stored in the products. The excess energy is released. Therefore, the reaction is exothermic.
Case 2: If the total amount of chemical energy stored in the products is great than that stored in the reactants. Energy is absorbed because the products have a greater amount of energy. Therefore, the reaction is endothermic.

2.
For each solution, the solute is represented by its chemical formula (NOT chemical equations), and the solution state is represented by the state symbol.
Sodium Hydroxide solution: NaOH(aq)
Sodium Hydrogen Carbonate solution: NaHCO3(aq)
Copper(II) Sulphate solution: CuSO4(aq)
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