👤
a fost răspuns

Determinati concentratia molara a urmatoarelor solutii :
a) in 200 mL solutie sunt dizolvati 20 mmoli NaOH
b) in 100 mL solutie sunt dizolvate 8g NaOH
c) se amesteca 200 g solutie de NaOH 20% (p=1,225 g/cm ³) cu 36,74 mL apa

Răspuns :

Mirceavaman
Cm=n/Vs iar in general: Vs=ms/d
a)20mmoli=0,02moli
Cm=n/Vs=0,02/0,2=0,1M
b)n=m/M=8/40=0,2moli
Cm=n/Vs=0,2/0,1=2M
c)c/100=md/ms => md=c*ms/100=40g NaOH
n=m/M=40/40=1mol
Vs=ms/d=200/1,225=163,26ml
Vsf=Vs+Vapa=200ml
Cm=n/Vs=1/0,2=5M

Alte intrebari