In an endothermic reaction,

### Heat is thought of as a reactant

## Step1: Understanding Endothermic Reactions### In an endothermic reaction, the system absorbs heat from its surroundings. This means that heat is required for the reaction to proceed.## Step2: Representing Heat as a Reactant### Since the system absorbs heat, it is treated as a reactant in the chemical equation. This implies that the reaction cannot occur without the input of heat.## Step3: Chemical Equation Representation### The chemical equation for an endothermic reaction includes heat as a reactant to indicate that it is absorbed during the reaction.