Question

differences
between exothermic and endothermic changes. For
each type of change, include at least two examples of
a physical process and of a chemical reaction.

Answer 1

Firstly, we will explain what is an exothermic reaction and an endothermic reaction.

Exothermic reaction:

An exothermic reaction is a process of when heat or energy is released from a matter to the environment it is in.

For Example:

Physical changes:

• When a candle is lit, by a matchstick the substances in a  candle reacts with the oxygen present in the air and create a  magnificent reaction with the flame that is produced. The energy is released and the reaction takes place
• Rusting of iron as water reacts with the iron particles and the layer of rust is seen on the substance. This is also an exothermic reaction.

Chemical Reaction

• When hydrochloric acid reacts with water, it creates a strong exothermic reaction because of the hydrogen ions reacts with water '
• HCl+ H2O= H3O+Cl + heat

Endothermic reaction:

An exothermic reaction is a process of when heat or energy is absorbed from a matter to the environment it is in.

For Example:

Physical Changes:

• When water evaporates, it absorbes the heat energy in the surrounding which allows the water to change states. Which is an endothermic reaction
• When you bake bread, in the oven the dough absorbes the energy around it which then allows the bread to be baked and rise. Which is also an endothermic reaction

Chemical changes:

• When you mix water with pottasium chloride
• KCl+ H2O+ heat= KCl (aqueous form)