When a substance burns in oxygen what happens to the amount of chemical energy?

When a substance burns in oxygen, the chemical energy stored in its bonds is released in the form of heat and light. This process, known as combustion, converts the chemical energy into thermal energy, which increases the temperature of the surrounding environment. Consequently, the amount of chemical energy in the original substance decreases as it transforms into energy in other forms. Overall, the total energy is conserved, as it is merely converted from one form to another.