1.Fe(NO3)3.
1)w(Fe)=Ar(Fe)/Mr(Fe(NO3)3)=56/242=0,2314(23,14%)
2)w(N)=Ar(N)*3/Mr(Fe(NO3)3)=42/242=0,1736(17,36%)
3)w(O)=1-w(Fe)-w(N)=1-0,2314-0,1736=0,595(59,5%).
2.C2H5OH.
1)w(C)=Ar(C)*2/Mr(C2H5OH)=24/46=0,5217(52,17%)
2)w(H)=Ar(H)*6/Mr(C2H5OH)=6/46=0,1304(13,04%)
3)w(O)=1-w(C)-w(H)=1-0,5217-0,1304=0,3479(34,79%).