дано
m(ppa BaCL2) = 350 g
+Na2SO4
m практ (BaSO4) = 18 g
η(BaSO4) =80%
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W(BaCL2)-?
m(BaSO4) = m практ (BaSO4)*100% / η(BaSO4) = 18*100% / 80% = 22.5
M(BaSO4) = 233 g/mol
n(BaSO4) = m(BaSO4) / M(BaSO4) = 22.5 / 233 = 0.097 mol
BaCL2+Na2SO4-->2NaCL+BaSO4↓
n(BaCL2) = n(BaSO4) = 0.097 mol
M(BACL2) = 208 g/mol
m(BaCL2) = n(BaCL2)*M(BaCL2) = 0.097*208 = 20.176 g
W(BaCL2) = m(BaCL2) / m рра(BaCL2) * 100% = 20.176 / 350 * 100% = 5.76%
ответ 5.76%