Question

Cate grame de solutie de NaOH de c=20% s-au folosit pentru neutralizarea a 1000 g solutie de HCl de c=36,5%?

Answer 1

-calculez masa de HCl din ms=1000g
c/100= md/ms
36,5/100= md/1000----> md=365gHcl
-calculez masa de NaOH care neutralizeaza  acidul, din ecuatia
1mol         1mol
NaOH  +  HCl---> NaCl  + H2O         M,NaOH=40g/mol;M,HCl= 36,5g/mol
23g..........36,5g
m=............365
m= 230gNaOH---.> este masa dizolvata in solutia de baza: calculez masa de solutie
20/100= 230/ms.............................> calculeaza !

Answer 2

Mai intii afla masele substantelor Astfel Omega(sub)=m(sub)*100%/m(sol) m(sub)=omega(sub)*m(sol)/100% m(HCl)=36,5*1000/100=365 (g) Scriem ecuatia reactiei NaOH+HCl=NaCl +H2O De aici obsercam optinem ecuatia x/40=365/36,5 x=10*40=400 g Acum aflam maaa solutiei m(solNaOH)=m(NaOH)*100%/omega(NaOH) m(solNaOH)=400*100/20=2000 (g)= 2 kg