Question

1. Cate g de S se gasesc in 5 moli H2SO4 ? 2. Sulfatul de Mg administrat intravenos,in solutie de 20%, are actiune sedativa. Concentratia procentuala a solutiei obtinute prin dizolvarea a 49,2 g MgSO4 ▪ 7H2O in 150,8g H2O este .. ?

Answer 1

1) mH2SO4=n*M=5*98=490g
98g H2SO4.............32g S
490g H2SO4.............Xg S
X=490*32/98=160g S
2) incepem prin calcularea masei cristalohidratului
M cristalohidrat=24 + 32 + 64 + 7*18=120 + 126=246g/mol
246 g.......120g MgSO4.......126g H2O
49,2g..........x g MgSO4............yg H2O
x=24g MgSO4 si y=25,2g H2O
md=24g MgSO4, ms=24+25,2+150,8=176g
c=md*100/ms=24*100/176=13,63%