Chemical reactions can change energy, and we can sort them into two main types: endothermic and exothermic.

1. Exothermic Reactions:

• These reactions give off energy. Most of the time, we see this energy as heat.
• For example, when we burn fuels like propane, it releases about 2,000 kJ of energy for every mole used.
• You can find these reactions in everyday processes like breathing and burning things.

2. Endothermic Reactions:

• These reactions take in energy from their surroundings.
• For instance, during photosynthesis, plants absorb about 2,800 kJ of energy for every mole of glucose they make.
• Often, these reactions cause the temperature in the surrounding area to drop.

Activation Energy:

• This is the lowest amount of energy needed to start a reaction.
• Depending on the materials involved and the conditions, this energy can be low (just a few kJ) or high (over 200 kJ).

Understanding these energy changes is really important. It helps us predict how reactions will behave and what the final results will be.