Question

se dizolva 50 g de sare in 250 ml de apa
a.) aflati concentratia apei
b.) daca se adauga 100ml apa, care este concentratia noii solutii?

Answer 1

2*58.5    2*18
2NaCl+2H2O=2NaOH+Cl2+H2
50g       x

M NaCl=23+35.5=58.5 g/mol sau u.m.
M H2O=2+16=18g/mol sau u.m.

x=(50*2*18)/(2*58.5)
x=1800/117
x=15.38 g H2O

C=md*100 /ms
C=15.38*100  /250
C=6.15%

C final=15.38*100/350
C final=4.39%