Science Assessment

Natural gas is a fossil fuel that is found deep beneath the surface of the earth. It is made mostly of methane. When natural gas is burned, methane reacts with oxygen to form carbon dioxide and water as represented below.

Methane + Oxygen → Carbon dioxide + Water

As methane reacts with oxygen, a flame is observed and the temperature of the surroundings increases.

What can you conclude about the amounts of energy in the chemical reaction system before the reaction occurs (only methane and oxygen are present) and after the reaction occurs (only carbon dioxide and water are present)?

1. The reaction system has less energy before the reaction occurs than after the reaction occurs.
2. The reaction system has more energy before the reaction occurs than after the reaction occurs.
3. The reaction system has the same amount of energy before and after the reaction occurs.
4. More information is needed to conclude anything about the amount of energy in the reaction system before and after the reaction occurs.