solutia1: ms1 = 200g c1 = 10% ⇒ md1 = 20g
oleum : m = 200g (0,8·200 = 160g H2SO4 + 0,2·200 = 40g SO3)
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final : ms = ms1+ m= 400g md= 20 +160 +49 229g ⇒ c= 229·100/400 =57,25%
SO3+H2O⇒H2SO4
nH2SO4 = nSO3 = 40/80 = 0,5 moli (m1 = 49g)