Veeaur õhus
b) 20 kg 0,4M lahuse (=1,004g/cm3) valmistamiseks.
Lahendus:
a) m(H2SO4)5% lahus=*V=1,02 g/cm3*20000cm3 = 20400g
m(H2SO4)=20400g*0,05=1020g
m(H2SO4)98% lahus = 1020g/0,98 = 1041g
V(H2SO4)98% lahus = m/ = 1041g/1,82g/cm3 = 572cm3 = 572ml
b) V(H2SO4)0,4M lahus = m/ = 20000g/1,004g/cm3 = 19920cm3 = 19,92L
n(H2SO4)0,4M lahus = c*V = 0,4M*19,92L = 7,97mol
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m(H2SO4) = n*M=7,97mol*98g/mol = 781g
m(H2SO4)98% lahus = 781g/0,98 = 797g
V(H2SO4)98% lahus = m/ = 797g/1,82g/cm3 = 438cm3 = 438ml
3. Kui palju vett on vaja lisada 50 liitrile 45% H3PO4 lahusele (=1,28g/cm3) 4%-lise lahuse
(=1,01g/cm3) saamiseks?
Lahendus:
m(H3PO4)45% lahus=*V=1,28g/cm3*50000cm3 = 64000g
m(H3PO4) = 64000g*0,45 = 28800g
m(H2O)45%-lises lahuses = 64000g-28800g = 35200g
m(H3PO4)4% lahus = 28800g/0,04 = 720000g
m(H2O)4%-lises lahuses = 720000g-28800g = 691200g
m(H2O)vaja lisada = 691200g-35200g = 656000g = 656kg = 656L
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