( ( During ( the explosion ) ) ( , ( ( chemical energy ) ( ( is ( converted ( to ( ( mostly light ) ( , ( ( heat and ) sound ) ) ) ) ) ) . ) ) ) )
(ROOT (S (PP (IN During) (NP (DT the) (NN explosion))) (, ,) (NP (NN chemical) (NN energy)) (VP (VBZ is) (VP (VBN converted) (PP (TO to) (NP (ADJP (RB mostly) (JJ light)) (, ,) (NN heat) (CC and) (NN sound))))) (. .)))
During  the explosion, chemical energy  is converted to mostly light,  heat  and sound.
(ROOT (S (S (NP (DT The) (NN energy)) (VP (VBZ transformations) (SBAR (IN that) (S (VP (VBP occur) (SBAR (WHADVP (WRB when)) (S (NP (DT a) (NN candle) (NNS burns)) (VP (VBZ is) (VP (VBN described) (PP (IN by))))))))))) (: :) (S (NP (NP (NN chemical) (NN energy)) (PP (IN from) (NP (DT the) (NN wax)))) (VP (VBZ is) (VP (VBN converted) (PP (IN into) (NP (NN light) (CC and) (NN heat) (NN energy)))))) (. .)))