A 40.80 gram sample of copper is heated in the presence of excess sulfur. A metal sulfide is formed with a mass of 51.09 g. Determine the empirical formula of the metal sulfide.

Cu₂S

Explanation:

From the question,

                     Cu                                 S

Mass:            40.80 g                      51.09-40.80 = 10.29 g

Mole ratio:     40.80/63.5                 10.29/32.1

                         0.64          :                0.32

Divide by the smallest,

                         0.64/0.32   :                0.32/0.32

                           2                :                  1

   Therefore,

Empirical formula = Cu₂S.

metric time was an attempt to create a standard unit of time based off of 10, but it never took off an is not included in the metric system (si)