Classify the following as an endothermic or exothermic reaction: a. making popcorn in a microwave oven.

Classify the following as an endothermic or exothermic reaction:

a. making popcorn in a microwave oven.

b. a burning match.

c. boiling water.

d. burning rocket fuel.

e. the reaction inside a heat pack

Answer

a. making popcorn in a microwave oven – an endothermic process

Preparing popcorn using a microwave oven is an endothermic process. In an endothermic reaction, the heat energy is taken from outside. Upon heating the popcorn in a microwave, moisture present inside each kernel forms steam that causes great pressure which then enables bursting kernels into fluffy white-looking ready popped popcorn. This transformation of liquid water to gas is a phase change that needs the input heat energy from an external microwave radiation. The popcorn kernels absorb thermal energy from their surroundings (the inside of the microwave) and use it as fuel for the reaction. Popcorn making is an endothermic process because when heat enters the system (the popcorn kernels). Due to the fact that popped popcorn has more thermal energy than unpopped kernels, it can be concluded from this observation that endothermic reactions take away and absorb energy as well as gain heat .

b. a burning match – an exothermic match.

c. boiling water – endothermic

d. burning rocket fuel – is exothermic

e. the exothermic reaction within a heat pack.