Question

pentru transformarea unei solutii diluate in solutii concentrate,se adauga un volum controlat de solutie de concentratie superioara sau o cantitate cunoscuta de substanta pura .Volumul de acid acetic glacial( c%=100. densitatea+ 1,0497 g/mL) caree se adauga peste 750 ml solutie apoasa de acid acetic (c%=30.densitatea=1,0383 g/mL),asfel incit solutia obtinuta sa fie de concentratie 50% este:
1)280g
2)150 mL
3)300 mL

Answer 1

d=ms/Vs => ms2=d2*Vs2=1,0383*750=778,725g solutie acid
c/100=md/ms => 100/100=md1/ms1 => md1=ms1
30/100=md2/778,725 => md2=778,725*30/100=233,6175g acid acetic
cf/100=mdf/msf
50/100=mdf/msf => msf=2mdf
msf=ms1+ms2=ms1+778,725
mdf=md1+md2=md1+233,6175=233,6175+ms1
ms1+778,725=2ms1+467,235
ms1=311,49g solutie acid acetic
Vs1=ms1/d1=311,49/1,0383=300ml