Question

Se amesteca: 60g sol NaOH 20% ,400gsolNaOH 5%,22g apa distilata si 0,45 moli NaOH. calculati concentratia procentuala a solutiei finale .

Answer 1

ms1=60g NaOH
Cp1=20%
ms2=400g 
Cp2=5%
mH2O=22g
n=0.45 moli NaOH
Din Cp1 =>md1=Cp1*ms1/100=20*60/100=12g
Din Cp2 =>md2=Cp2*ms2/100=5*400/100=20g
Din n=md3/M, MNaOH=40g/mol, md3=0.45*40=18g
mdf=md1+md2+md3=12+20+18=50g
msf=ms1+ms2+mH2O=60+400+22=482g
Cpf=mdf/msf*100=50/482*100=10.37%