Question

Aluminium reacts with hydrogen chloride to produce ${{H}_{2}}$ according to the equation $2Al\,+\,6HCl\,\to \,\,\,2AlC{{l}_{3}}\,+\,3{{H}_{2}}$
Then 2 grams of ${{H}_{2}}$ would be produced from
(A) 1 mole of Al
(B) 2 moles of Al
(C) 2/3 mole of Al
(D) 3/2 mole of Al

Answer 1

A balanced reaction is already provided to us. 1 g of hydrogen represents 1 mole of hydrogen. Now we will calculate the number of moles of aluminium needed in the reactant side to obtain 1 mole of hydrogen. With this we can determine the correct answer.

Complete step-by-step answer:
As mentioned in the hint, we know that 2 grams of hydrogen make up 1 mole of hydrogen molecules. In the reaction, $2Al\,+\,6HCl\,\to \,\,\,2AlC{{l}_{3}}\,+\,3{{H}_{2}}$
We see that 2 moles of aluminium yield 3 moles of hydrogen molecules as a product. With this we will determine the amount of aluminium required to produce 1 mole of hydrogen. 2 moles of Al give 3 moles of hydrogen. So, x moles of Al will give 1 mole of hydrogen where x is an arbitrary variable. The value of x turns out to be 2/3. So, 2/3 mole of Al produces 1 mole of hydrogen molecule at the specified temperature and pressure.

Therefore, the correct answer is option (C).

Note: It is important to know that hydrogen always exists in diatomic form and not in monatomic form in nature. This is the reason the mass of 1 mole of hydrogen gas is 2 g as it contains 2 atoms of hydrogen in 1 molecule.