A trivalent metal weighing 32.4 g was dissolved in sulfuric acid, while hydrogen was evolved

A trivalent metal weighing 32.4 g was dissolved in sulfuric acid, while hydrogen was evolved with a volume of 40.32 liters. Identify this metal?

Let M be an unknown trivalent metal.

Let’s write the reaction equation:

2M + 3H2SO4 = M2 (SO4) 3 + 3H2 ↑

Let’s find the amount of metal substance M:

v (M) = m (M) / M (M) = 32.4 / M (M) (mol).

Let’s find the amount of substance hydrogen:

v (H2) = V (H2) / Vm = 40.32 / 22.4 = 1.8 (mol).

According to the reaction equation, for 2 mol of M, 3 mol of H2 are formed, therefore:

v (M) * 3 = v (H2) * 2,

(32.4 / M (M)) * 3 = 1.8 * 2,

M (M) = 27 (g / mol), which corresponds to the metal aluminum (Al).

Answer: aluminum (Al).