Question

Question #71b30

Answer 1

The % of water is 44.8 so the % of the Al chloride must be 100 - 44.8 = 55.2

Ratio in grams Al : Cl =

1 : 3.95

Ratio in moles :

1/27 : 3.95/35.5 --->

0.037 : 0.11 ---->

1 :3

So `AlCl_3` must take up 55.2 % of the mass and `H_2O` must take up 44.8 % of the mass.

The `M_r` of `AlCl_3` is 27 + (3 x 35.5) = 106.5

The `M_r` of `H_2O` is (2 x 1) + 16 = 18

So the ratio in moles ------>

55.2/106.5 : 18/44.8

Which is : 0.518 : 0.4

1 : 0.77

4 : 3

i.e `(AlCl_3)_4.(H_2O)_3`

This is a strange question as no compound like this could ever exist. Aluminium chloride reacts immediately with moisture and is hydrolysed to give `Al_((aq))^(3+)` and `HCl_((aq))`.