Natural gas is a fuel that is used for heating and cooking in many homes, schools, and office buildings. It is composed of almost pure methane (CH$$) and burns with a hot, blue flame. The chemical equation for the burning of methane is shown below: CH4 + 2O2→CO2 + 2H2O

Describe in detail the burning of methane as a chemical reaction. Be sure to include the following information in your description:

Explain how you can tell from the chemical equation that this is a chemical reaction and not just a physical change.
Cite two observations that would likely indicate that a chemical reaction is occurring.
Classify the reaction as endothermic or exothermic and cite evidence for your choice.
Identify the reactants and the products of the reaction.
Explain how the chemical equation shows that the Law of Conservation of Mass is satisfied in this reaction.