4.8 g of magnesium was dissolved in an excess of hydrobromic acid. Find the volume of released gas.

The reaction equation for the dissolution of magnesium in hydrobromic acid:

Mg + 2HBr = MgBr2 + H2 ↑

Amount of dissolved magnesium substance:

v (Mg) = m (Mg) / M (Mg) = 4.8 / 24 = 0.2 (mol).

According to the reaction equation, from 1 mole of Mg, 1 mole of H2 is formed, therefore:

v (H2) = v (Mg) = 0.2 (mol).

Thus, the volume of hydrogen gas evolved under normal conditions (n.o.):

V (H2) = v (H2) * Vm = 0.2 * 22.4 = 4.48 (l).

Answer: 4.48 l.