As a result of the combustion of a bivalent metal with a mass of 2 g, an oxide with a mass of 2.8

As a result of the combustion of a bivalent metal with a mass of 2 g, an oxide with a mass of 2.8 g was obtained. Set the name of the metal.

The equation for the reaction of an unknown divalent metal with oxygen:

2M + O2 = 2MO, where M is an unknown divalent metal.

Amount of substance M:

v (M) = m (M) / M (M) = 2 / M (M) (mol).

MO substance quantity:

v (MO) = m (MO) / M (MO) = 2.8 / (M (M) + 16) (mol).

According to the reaction equation, 2 mol MO is formed from 2 mol of M, therefore:

v (M) = v (MO),

2 / M (M) = 2.8 / (M (M) + 16),

whence we find M (M) = 40 (g / mol), which corresponds to the metal calcium (Ca).