Question

Un volum de 100ml HCl 20% si densitatea=1.1 g/cm cub se dilueaza cu 600 ml H2O cu densitatea=1g/cm cub. Afirmatiile corecte sunt:
A) Solutia are masa de 710g
B) Solutia contine 20g solut
C)Solutia contine 0,8 moli solut
D)Solutia are CM=8,6x10 la -1M
E)C%=4%

Answer 1

ro=ms/V => ms=ro*V = 1,1*100 = 110g sol HCl

C=md/ms*100 => md=C*ms/100 = 20*110/100 = 22g HCl 

n=md/M = 22/36,5 = 0,6 moli HCl

ms final = 110+600 = 710g sol => A- adevarat

B)- fals

C) n=m/M = 600/18 = 33,33 moli H2O + 0,6 moli 33,933 moli solutie..
=> C-fals

D) Vsf = 100+700 = 0,7 L

Cmf = n/Vsf  = 0,6/0,7 = 0,861 moli/L sau 8,61*10^(-1) mol/L => D-adevarat

E) Cf=mdf/msf*100 = 22/710*100 = 3,098%