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

1 Answer
anor277
Jan 28, 2017

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

Explanation:

#H_2O(l) rarr H_2O(s) + 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:

#CH_4(g) + O_2(g) rarr CO_2(g) + 2H_2O(l) + 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).

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