Question

In 4 vase ce contin cite 250 g de solutie de hidroxid de potasiu cu partea de masa de 20%s-a adaugat respectiv..a)200g de apa.. b)500g de apa..c)1 l de apa.d)350 ml de apa.
Stabileste partea de masã KOH in fiecare din solutiile diluate.

Answer 1

Se da:
msol(KOH)=250g
W(KOH)=20%
a)m(H2O)=200g
b)m(H2O)=500g
c)V(H2O)=1l
d)V(H2O)=350ml
Wsol(KOH)=?%

R-re:
Wsold(KOH)=m(KOH)/msold(KOH)*100%

msold(KOH)=m(KOH)+m(H2O)

a)msold(KOH)=250+200=450g⇒Wsold(KOH)=250/450*100%=55,56%
b)msold(KOH)=250+500=750g⇒Wsold(KOH)=250/750*100%=33,34%
La c) si d) m(H2O)=V(H2O)*p(H2O), p(H2O)=1g/cm³
c)1l=1dm³=1000cm³
m(H2O)=1000*1=1000g
msold(KOH)=250+1000=1250g⇒Wsold(KOH)=250/1250*100%=20%
d)350ml=350cm³
m(H2O)=350*1=350g
msold(KOH)=250+350=600⇒Wsold(KOH)=250/600*100%=41,67%