Дано
m(ppa K2SO4) = 60 g
W(K2SO4) = 4%
+m2(K2SO4)= 5.6 g
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W1-?
m(K2SO4)= m(ppa K2SO4)*W(K2SO4) / 100% = 60*4%/100%=2.4 g
m1(ppa K2SO4) = m(ppa K2SO4)+m2(K2SO4) = 60+5.6= 65.6 g
m1(K2SO4) = m(K2SO4)+m2(K2SO4)= 2.4+5.6 = 8 g
W1(K2SO4) = m1(K2SO4) / m1(ppa K2SO4)/100%= 8/65.6*100%=12.12%
ответ 12.12%