Răspuns:
a. in 100g solutie.........3gNa2CO3
200g..............................X= md=6g
m,apa= ms-md=200-6=> 194g---> v,apa= 184ml
b. in 100g sol...........5gNa2CO3
200g.....................x=md= 10g
m,apa= 200-10=>190g----> v,apa= 190ml
c. in 100g sol..............2g Na2CO3
200g...........................x= md=4g
m,apa= 200-4=> 196g---> v,apa= 196ml
se stie ca densitatea apei este 1 g/ml
Explicație: