"1041g" - 1 õppematerjal

Veeaur õhus

Lahendus: Võtame 1,0L=1000cm3 5M H2SO4 lahust. m(H2SO4)lahus = *V=1,45g/cm3*1000cm3 = 1450g n(H2SO4) = c*V=5M*1L = 5mol m(H2SO4) = n*M=5mol*98g/mol = 490g %(H2SO4) = (490g/1450g)*100% = 33,8% 2. Mitu milliliitrit kontsentreeritud H2SO4 (98%), =1,82g/cm3 on vaja: a) 20 liitri 5% lahuse (=1,02g/cm3) valmistamiseks 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 3 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