解：設(shè)參加反應(yīng)的二氧化硫的質(zhì)量為?$x。$?
?$\mathrm {SO}_2＋2\mathrm {H}_2\mathrm {O}＋\mathrm {I}_2\xlongequal[ ]{ }\mathrm {H}_2\mathrm {SO}_4＋2\mathrm {HI}$?
64 254
? $x$? 2.54mg
?$\frac {64 }{254 }=\frac {x }{2.54\mathrm {mg} }，$?解得?$x=0.64\mathrm {mg}$?
則?$1.0\mathrm {m}^3$?空氣中?$\mathrm {SO}_2$?的質(zhì)量為?$0.64\mathrm {mg}÷2=0.32\mathrm {mg}$?
答：?$1.0\mathrm {m}^3$?空氣中?$\mathrm {SO}_2$?的質(zhì)量為?$0.32\mathrm {mg}。$?
