Question

120g solutie HCl de concentratie c=30% reactioneaza cu 100g KOH de concentratie c=25%.
a) masa substanta exces
b) Concentratie solutie finala

Va rog!!

Answer 1

c= mdx100/ms.unde ms= md+m,apa
-calculez masa de acid: 30/100=md/120---> md=36gHCl; m.apa=84g
-calculez masa de baza :25/100= md/100--->md=25gNaOH;m,apa=75g
ecuatia reactiei este 
1mol     1mol         1mol     1mol
HCl  + NaOH----> NaCl + H20
36,5g.....40g.........58,5g.....18g
x.............25.............y............z   acidul este in esces
x= 22,81g  HCl---.> m,exces= 36g-22,8g= 13,2g HCl
y=36,56g   NaCl
z=11,25g H2O

in solutia finala se gasesc dizolvate excesul de acid si sarea formata
md= 13,2+36,56=49,76g
m,apa= 84+75+11,25=170,25g
ms= md+m,apa= 49,76+170,35=.....................
c= mdx100/ms.... inlocuieste si finalizeaza calculele !!!!