Question

Aluminium carbide reacts with water according to the following equation.
$A{l}_4{C}_3+12H_{2}O\to 4Al(OH{)}_3+3C{H}_4$
(i) What mass of aluminium hydroxide is formed from $12$g of aluminium carbide?
(ii) What volume of methane at s.t.p. is obtained from $12$g of aluminium carbide?

Answer 1

Molecular weight of $A{l}_4{C}_3$ is 144 g/mol, $Al(OH{)}_3$ is 78 g/mol and $C{H}_4$ is 16 g/mol.

(i)In the reaction:

144 g of $A{l}_4{C}_3$ gives 312 g $Al(OH{)}_3$

Therefore 12 g will give $12\times \frac{312}{144}=26gAl(OH{)}_3$

(ii) 144 g of $A{l}_4{C}_3$ gives 48 g $C{H}_4$

Therefore 12 g will give $12\times \frac{48}{144}=4gC{H}_4$

Since 1 mol of gas at STP occupies a volume of 22.4 L

Therefore, volume occupied by 4 g $C{H}_4$ is:

$22.4\times \frac{4}{16}=5.6LC{H}_4$