①知道溶液質(zhì)量m(溶液)和溶質(zhì)質(zhì)量m(溶質(zhì))，則溶質(zhì)的質(zhì)量分數(shù)為W(%)=[m(溶質(zhì))/m(溶液)]×100%;

②知道溶劑的質(zhì)量m1和溶質(zhì)的質(zhì)量m2,則溶質(zhì)的質(zhì)量分數(shù)為W(%)=[m2/(m1+m2)]×100%;

③知道溶液的質(zhì)量m和溶劑的質(zhì)量m0,則溶質(zhì)的質(zhì)量分數(shù)為W(%)=[(m-mo)/m]×100%;。