# Is water freezing to ice endothermic or exothermic? Natural gas burning?

Jan 28, 2017

Well, you are making bonds, so we would assume ice formation to be exothermic.....

#### Explanation:

${H}_{2} O \left(l\right) \rightarrow {H}_{2} O \left(s\right) + \Delta$

When natural gas is burned, the reaction is much less ambiguous. Strong $C = O$ and $H - O$ bonds are formed, which are stronger than the $C - H$ and $O = O$ bonds that are broken:

$C {H}_{4} \left(g\right) + {O}_{2} \left(g\right) \rightarrow C {O}_{2} \left(g\right) + 2 {H}_{2} O \left(l\right) + \Delta$

This reaction is appreciably and measurably exothermic, and is probably heating your home right now (well it would be if you live in the northern hemisphere).