дано
w(BaCL2) = 5%
m(BaSO4) = 23.3 g
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m(ppa BaCL2)-?
BaCL2+Na2SO4-->BaSO4+2NaCL
M(BaSO4) = 233 g/mol
n(BaSO4) = m/M = 23.3 / 233 = 0.1 mol
n(BaCL2) = n(BaSO4) =0.1 mol
M(BaCL2) = 208 g/mol
m(BaCL2) = n*M = 0.1*208 = 20.8 g
m(ppa BaCL2) = m(BaCL2) * 100% / W(BaCL2) = 20.8 * 100% / 5%
m(ppa BaCL2)= 416 g
ответ 416 г