Question

Which piece of evidence would prove that a reaction is exothermic?
There is a phase change during the reaction.
One of the reactants is baking soda.
The reactants have more energy than the products.
There are more moles of gas in the products than in the reactants.

Answer 1

The reactants have more energy than the products. If a reaction is EXOthermic, it loses energy during the reaction, so the output (products) will have less energy than the input (reactants).

Answer 2

Answer: Option (c) is the correct answer.

Explanation:

In an exothermic reaction, excess of energy is released into the surroundings as a result there occurs decrease in the energy of products.

For example, $A + B \rightarrow C + D + Heat$ is an exothermic reaction.

Whereas in an endothermic reaction, energy is absorbed by reactant molecules and therefore, energy of products is more than energy of reactants.

For example, $A + B + Heat \rightarrow C + D$ is an endothermic reaction.

Thus, we can conclude that the reactants have more energy than the products is a piece of evidence that would prove that a reaction is exothermic.