Question

In urma introducerii intr-un pahar Berzelius a 50 g solutie de NaOH 40 % si 50 g solutie de HCl 36,5 % se va obtine o solutie de ce concentratie?

Answer 1

-solutia  de baza  contine 20g NaoH*, (50-20)g apa
-solutia de acid contine 18,25g HCL* , (50-18,25)g apa
-ecuatia reactiei 
NaOH  + HCl   -------> NaCl   + H2O
40g..........36,5g............58,5g.........18g
20g...........18,25g          29,25g         9g
- se consuma toata masa de baza si de acid si se formeaza 29,25g sare, care este md in solutia formata
- masa de apa : m= 30+31,75+9=70,75g
-masa de solutie: ms= md+m,apa= > 70,25+70,75=>100g
-conc. procentuala a solutiei formate dupa terminarea reactiei
c/100= md/ms---> c= 29,25x100/100= 29,25%
* md baza si acid sunt scoase din relatia c/100= md/ms---> md