The combustion of methane(CH4) produces energy. Where does this energy come from?

The combustion of methane produces energy that comes from the formation of bonds in the products.

Methane is a hydrocarbon formed as a result of a carbon atom bonding with 4 hydrogen atoms.

When burned in oxygen, methane produces carbon dioxide and water as products.

The breakage of the bond in the methane consumes energy while the formation of carbon dioxide and water molecules produces energy. However, the latter is much more than the former.

Thus, there is net energy that is released when methane undergoes combustion.

More on enthalpy of reactions can be found here; link

Explanation:

Combustion produces energy. Where does all this energy come from? Energy is stored in the chemical bonds that hold the carbon and hydrogen atoms together. When the atoms are rearranged, the bonds are broken, releasing energy.

a. the law of proportion states the combination of 2 atoms in a specific ratio to produce multiple compounds such as the given statement of question ‘1st compound contains 88.8 % cu ’ indicates 88.8 g of cu is present along with 11.2 g oxygen in 100 g of compound whereas the statement ‘2st compound contains 79.9 % cu ’ indicates 79.9 g of cu is present along with 20.1 g oxygen in 100 g of compound

1st compound contains 88.8 g cu

for cu

m = 63 g /mol

atomic % = 88.8 /63 = 1.42

for o

m = 16 g /mol

atomic % = 11.2 /16 = 0.7

b. the emperical formula of 1st compound is

cu1.4o0.7

cu2o