Răspuns:
Explicație:
ms NaOH= 300g , c=20%
r. cu FeCl3
masa de precipitat
-se afla md sol. de NaOH
md= c.ms : 100
md= 300. 20 :100=60g NaOH
60g xg
3NaOH + FeCl3=3 NaCl + Fe(OH)3
3.40g 107g
x= 60 . 107 : 120=53,5 g precipitat
n=53,5g : 107g/moli=0,5moli
MNaOH=23+16+1=40------>40g/moli
MFe(OH)3=56 +2+3.16 +3=107 ------>107g/moli