The interaction of 12.8 g of a divalent metal with chlorine yields 27 g of metal chloride. Determine the metal.

The reaction equation for the formation of chloride of an unknown divalent metal:

M + Cl2 = MCl2, where M is an unknown divalent metal.

Amount of substance M:

v (M) = m (M) / M (M) = 12.8 / M (M) (mol).

The amount of substance MCl2:

v (MCl2) = m (MCl2) / M (MCl2) = 27 / (M (M) + 35.5 * 2) = 27 / (M (M) + 71) (mol).

According to the reaction equation, from 1 mol of M, 1 mol of MCl2 is formed, therefore:

v (M) = v (MCl2),

12.8 / M (M) = 27 / (M (M) + 71),

whence we find M (M) = 64 (amu), which corresponds to copper (Cu).