Veeaur õhus
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
4. Kui palju booraksit, Na2B4O7·10H2O, on vaja kaaluda 7 dm3 11%-lise vesilahuse
(=1,16g/cm3) valmistamiseks?
Lahendus:
m(Na2B4O7)11% lahus = *V = 1,16g/cm3*7000cm3 = 8120g
m(Na2B4O7) = 8120g*0,11 = 893,2g
Na2B4O7·10H2O Na2B4O7 + 10H2O
n(Na2B4O7) = m/M = 893,2g/202g/mol = 4,42mol
m(Na2B4O7·10H2O) = n*M = 4,42mol*382g/mol = 1688g
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