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.

n+h→nh3

we must remember that nitrogen and hydrogen are both diatomic molecules in their standard gas form. this adjusts the equation to

n2+h2→nh3

now we need to adjust coefficients in order to balance the atoms on each side of the equation. currently we have 2 atoms of nitrogen and 2 atoms of hydrogen on the reactant side and 1 atom of nitrogen and 3 atoms of hydrogen on the product side.

we can balance the hydrogens by placing a coefficient of 2 in front of ammonia and a coefficient of 3 in front of the hydrogen.

n2+3h2→2nh3

this gives us 6 hydrogen on each side and coincidentally the nitrogens now equal 2 on each side.