Question

Se amesteca 100mL solutie H2SO4 de c=25% si densitate=1,18g/mL cu 500mL solutie H2SO4 de CM= 0,5 mol/L si cu 200mL solutie H2SO4 de CM=1 mol/L. Calculati CM a solutiei finale.
AH=1; AS=32; AO=16

Answer 1

cm3=mL

Vs1=100mL=0.1L
C1=25%
ro1=1,18g/cm3

Vs2=500mL=0.5L
Cm2=0.5 mol/L

Vs3=200mL=0.2L
Cm3=1 mol/L

Din ro1==>ro=ms1/Vs1==>ms1=ro1*Vs1=1.18g/cm3*100cm3=118g sol. H2SO4

C1=md1/ms1*100==>md1=C1*ms1/100=25*118/100=29.5g

n1=md/M=29.5/98=0.3 moli

Din Cm2==>Cm2=n2/Vs2==>n2=Cm2*Vs2=0.5*0.5=0.25 moli

Din Cm3=n3/Vs3==>n3=Cm3*Vs3=1*0.2=0.2 moli

nt=n1+n2+n3=0.3+0.25+0.2=0.75 moli

Vsf=Vs1+Vs2+Vs3=100+500+200=800mL=0.8L

Cmf=nt/Vsf=0.75/0.8=0.9375 moli/L

MH2SO4=98g/mol