解：設(shè)參加反應(yīng)的過氧化氫的質(zhì)量為??$x。$??
??$2\mathrm {H}_2 \mathrm {O}_2\xlongequal[ ]{ \mathrm {MnO}_2}2 \mathrm {H}_2 \mathrm {O}+ \mathrm {O}_2↑ $??
68 32
??$x$?? 1.6g
??$\frac { 68}{ x }=\frac { 32 }{ 1.6 \mathrm {g} }，$??解得??$ x =3.4 \mathrm {g} $??
參加反應(yīng)的過氧化氫的溶質(zhì)質(zhì)量分數(shù)為??$\frac {3.4 \mathrm {g}}{ 68 \mathrm {g}}×100％= 5％$?
?
答：參加反應(yīng)的過氧化氫的溶質(zhì)質(zhì)量分數(shù)為??$5％。$??
