CH3COOH
M(CH3COOH) = 2*M© + 4*M(H) + 2*M(O) = 2*12 + 4*1 + 2*16 = 24 + 4 + 32 = 60 г/моль w( C ) = 2*M( C )*100%/M(CH3COOH) = 2*12*100%/60 = 40% w( H ) = 4*M( H )*100%/M(CH3COOH) = 4*1*100%/60 = 6,67% w( O ) = 2*M( O )*100%/M(CH3COOH) = 2*16*100%/60 = 53,33%