Question

1.Peste 200g de acid clorhidric de concentratie 18,25% se adauga solutie de hidroxid de sodiu de concentratie 20% pana la neutralizarea completa a acidului. Determinati concentratia procentuala a solutiei de sare obtinuta la final?

2.Peste 200g solutie de hidroxid de sodiu c=10% se adauga 23g sodiu. Determinati concentratia procentuala a solutiei obtinute?

Va rog ajutati-ma ... la primele 2 raspunsuri dau cel mai bun raspuns!

Answer 1

Calculam masa de acid din solutie
c/100=md/ms => md=c*ms/100=18,25*200/100=36,5g HCl
MNaOH=23+16+1=40g/mol
MHCl=1+35,5=36,5g/mol
40g.......36,5g
NaOH + HCl -> NaCl + H2O
x=?........36,5g
x=40*36,5/36,5=40g NaOH
mNaOH=md
c/100=md/ms => ms=md*100/c=40*100/20=200g solutie
2)
c/100=md/ms => md=c*ms/100=10*200/100=20g NaOH
ms=md+mapa => mapa=200-20=180g apa
Na va reactiona cu o parte din apa
23g...18g.......40g
Na + H2O -> NaOH + ½H2
23g...18g.......40g
mdfinal=md+40=20+40=60g
msfinal=ms-18+40=200+22=222g solutie
cf=mdf*100/msf=60*100/222=27,02%