Question

calculaţi masa de NaOH care reacţionează cu 130 g de soluţie de FeCl3 de concentraţie 5%

Answer 1

3NaOH+FeCl3=Fe(OH)3+3NaCl

130 g sol FeCl3(ms)

c=5%   c/100=md/ms=>md=c x ms/100=5x130/100=5x1,3=6,5g FeCl3

M FeCl3=56+35,5x3=56+106,5=162,5g/mol

numarul de moli=6,5/162,5=0,04 moli

1 mol FeCl3..................3 moli NaOH

0,04..................................0,12 moli NaOH

M NaOH=40g/mol

m=0,12x40=4,8g NaOH