1.
Notam cu c concentatia
c/100=200/1200
c/100=2/12
c/100=1/6
c=100·1/6
c=100/6
c=16,(6)%
2.
c=25% inseamna ca
cantitatea de H2O=75% din solutie
calculam:
75%·800=75/100·800=75/1·8=75·8=600g H2O
3.
Fie ms masa solutiei; ms=500g
Fie md masa dizolvatului
c=10%
stiind ca
c/100=md/ms
10/100=md/500
1/10=md/500
md=1·500/10
md=500/10
md=50g sare de lamaie