Question

if two moles of aluminium releases 3 moles of hydrogen gas based on the given chemical equation
2A1 + xHCI --> 2AlCl3 + 3H2
Then the amount of HCl required for evolution of 6g of hydrogen gas is
(A) 3 moles
(B) 6 moles
(C) 12 moles
(D) 4 moles​

Answer 1

Answer:

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Answer 2

Explanation:

The balanced chemical equation:

6HCl(aq) + 2Al(s) = 2AlCl3(aq) + 3H2(g)

According to the chemical equation: n(Al)/2 = n(H2)/3

The ideal gas law can be used to calculate the amount of H2:

PV = nRT

n= PV/RT

Thus:

n(H2) = (100 kPa × 0.5 L) / (8.314 kPa L K-1 mol-1 × 298 K) = 0.02 mol

n(Al)/2 = n(H2)/3

n(Al) = 2 × n(H2) / 3 = 2 × (0.02 mol) / 3 = 0.0133 mol

Moles of Al = Mass of Al / Molar mass of Al

The molar mass of Al is 27 g/mol

Thus:

Mass of Al = n(Al) × M(Al) = (0.0133 mol) × (27 g/mol) = 0.3591 g = 0.36 g

Answer: 0.36 g of aluminum (Al) is needed.