Ответ:

Объяснение:

1)

М(CrO3) = Ar(Cr) + Ar(O) * 3 = 52 + 16 * 3 = 100

w(Cr) = Ar(Cr) * n /М(CrO3) * 100% = 52/100 * 100% = 52%

w(О) = Ar(О) * n /М(CrO3) * 100% = 16 * 3/100 * 100% = 48%

2)

М(Al2(SO4)3) = Ar(Al) * 2 + Ar(S) * 3 + Ar(O) * 12 =

= 27 * 2  + 32 * 3 + 16 * 12 = 342

w(Al) = Ar(Al) * n /М(Al2(SO4)3) * 100% = 27 * 2/342 * 100% = 15,79%

w(S) = Ar(S) * n /М(Al2(SO4)3) * 100% = 32 * 3/342 * 100% = 28,07%

w(О) = Ar(О) * n /М(Al2(SO4)3) * 100% = 16 * 12/342 * 100% = 56,14%

3)

М(Na2SO4) = Ar(Na) * 2 + Ar(S) + Ar(O) * 4 = 23 * 2 + 32 + 16 * 4 = 142

w(Na) = Ar(Na) * n /М(Na2SO4) * 100% = 23 * 2/142 * 100% = 32,39%

w(S) = Ar(S) * n /М(Na2SO4) * 100% = 32/142 * 100% = 22,54%

w(О) = Ar(О) * n /М(Na2SO4) * 100% = 16 * 4/142 * 100% = 45,07%