вычислить массовые доли элементов: AL₂(SO₄)₃ , 
K₂SO₄

Al2(SO4)3
w(Al) = 2Ar(Al)/Mr(Al2(SO4)3) = 54/342 = 0,16 = 16%
w(S) = 3Ar(S)/Mr(Al2(SO4)3) = 96/342 = 0,28 = 28%
w(O) = 12Ar(O)/Mr(Al2(SO4)3 = 192/342 = 0,56 = 56%
K2SO4
w(K) = 2Ar(K)/Mr(K2SO4) = 78/174 = 0,45 = 45%
w(S) = Ar(S)/Mr(K2SO4) = 32/174 = 0,18 = 18%
w(O) =4Ar(O)/Mr(K2SO4) = 64/174 = 0,37 = 37%