Chemical Energy
Chemical Energy is energy stored inside a substance that comes out when it burns or reacts.
Think of it this way
A match sits in a box on the kitchen table. It looks still and cold — no heat, no light. Strike it against the box and a flame appears, giving off heat and light. That energy was stored inside the match tip the whole time, locked in place until the strike set it free.
Explaining chemical energy by grade level
Food like a peanut holds energy inside it. When you burn a peanut, that hidden energy comes out as heat. The heat from one small peanut can warm up a cup of water. Your body uses that same stored energy when you eat food.