Răspuns:
Explicație:
4.
520g Zn ,p=75%
react. cu HCl
masa de sare
-se afla masa pura de Zn
mp= p . mi :100
mp= 75 . 520 : 100=390 g Zn pur
390g xg
Zn +2 HCl= Zn Cl2 + H2
65g 136g
x= 390 . 136 : 65=816 g ZnCl2
n= 816 g : 136g/moli=6 moli ZnCl2
M ZNCl2= 65 + 2.35,5=136------> 136g/moli
5.
Fenolftaleina in mediu bazic se coloreaza in rosu- carmin
