when 4.008 g of calcium metal is heated in the air, the sample gains 1.600 g of oxygen in forming the oxide. Calculate the empirical formula of the calcium oxide.

CaO

Explanation:

Firstly, let's get the percentage compositions.

The total mass is now = 4.008 + 1.600 = 5.608g

The percentage composition of carbon is thus 4.008/5.608 * 100 = 71.47%

The percentage composition of oxygen is 100 - 71.4 = 28.53%

Now, we divide each percentage by the atomic masses. The atomic mass of calcium is 40 while that of oxygen is 16

Ca = 71.47/40 = 1.78675

O = 28.53/16 = 1.783125

Both values are quite similar and dividing by the smallest will yield same values of 1.

Hence, the empirical formula is caO