Question

Aluminium carbide reacts with water to form:
A. Methane
B. Ethane
C. Ethene
D. Ethyne

Answer 1

Hint: Attempt this question by writing the chemical formula of aluminium carbide and water. You will see that an alkane is formed as the end product in this reaction along with a hydroxide of aluminium.

Complete step by step answer:
The chemical formula of aluminium carbide and water is$(A{{l}_{4}}{{C}_{3}})$ and $({{H}_{2}}O)$ respectively. Aluminium carbide, as the name suggests, is a carbide of aluminium. It occurs as pale yellow to brown crystals. In aluminium carbide, each aluminium atom is coordinated to 4 carbon atoms and therefore it has a tetrahedral geometry.
It shows stability up to 1400 °C. It decomposes in water with the production of methane.
The equation for the reaction of aluminium carbide with water is given as –
$A{{l}_{4}}{{C}_{3}}(s)+12{{H}_{2}}O(l)\to 4Al{{(OH)}_{3}}(s)+3C{{H}_{4}}(g)$
From the reaction, we can see that 1 mole of aluminium carbide $(A{{l}_{4}}{{C}_{3}})$ reacts with 12 moles of water $({{H}_{2}}O)$to give 4 moles of aluminium hydroxide $(Al{{(OH)}_{3}})$ and 3 moles of methane gas $(C{{H}_{4}})$.
From the above reaction, we can say that aluminium carbide decomposes in water to produce methane.
Therefore, the answer is option (a) – Methane - $C{{H}_{4}}$

Additional information: Aluminium carbide shows a similar reaction with any proton giving compound. For example, when aluminium carbide reacts with hydrogen chloride –
$A{{l}_{4}}{{C}_{3}}+12HCl\to 4AlC{{l}_{3}}+3C{{H}_{4}}$
As we can see, in this reaction too, methane is formed.

Note: The above reaction is an example of hydrolysis. Reaction of a compound with water is known as a hydrolysis reaction.