Question

intr-un cristalizator cu 200g apa se introduc 4.6g Na . ce concentratie va avea solutia de NaOH obtinuta ?

Answer 1

nNa = 4,6/23 = 0,2 moli

Na + H2O => NaOH + 1/2H2

nNa=nH2O=nNaOH= 0,2 moli

nH2=0,5*nNa=0,5*0,2 = 0,1 moli

m H2O = 0,2*18 = 3,6g
m NaOH = 0,2*40 = 8g
m H2 = 0,1*2 = 0,2g

md = 8g

msf = 200+8+4,6-3,6-0,2 = 208,8g

Cf = 8/208,8*100 = 3,83%