Question

Care este masa solutiei de acid clorhidric de concentratie 36,5% necesara neutralizari a 250 de grame solutie de hidroxid de natriu de concentratie 20%.ROG SERIOZITATE SI REZOLVAREA PROBLEMEI GRAME SI IN MOLI.

Answer 1

Datele problemei:
c(HCl)=36,5%
ms(NaOH)=250g
c(NaOH)=20%

Ce trebuie aflat:
ms(HCl)=?

Rezolvare:
NaOH+HCl=NaCl+H2O
M(NaOH)=40g/mol    M(HCl)=36,5g/mol
c=md/ms*100=>md=c*ms/100
md(NaOH)=20*250/100=50g (masa de hidroxid care reactioneaza)
n(NaOH)=md/M(NaOH)=>n(NaOH)=50/40=1,25 moli

1 mol NaOH.....(reactioneaza cu).....1 mol HCl
1,25 moli NaOH.....(reactioneaza cu).....x moli HCl
x=1,25 moli HCl
md(HCl)=1,25*36,5=45,625g
ms(HCl)=md*100/c=45,625*100/36,5=125g