A 43.56 gram sample of iron is heated in the presence of excess sulfur. A metal sulfide is formed with a mass of 81.08 g. Determine the empirical formula of the metal sulfide.

Fe2S3

Explanation:

Data obtained from the question include:

Mass of Fe = 43.56g

Mass of metal sulfide = 81.08g

Next we shall determine the mass of sulphur, S in the compound. This is illustrated below:

Mass of S = Mass of metal sulfide - mass of Fe

Mass of S = 81.08 - 43.56 = 37.52g

The empirical formula for the metal sulfide can be obtain as follow:

Fe = 43.56g

S = 37.52g

Divide by their molar mass

Fe = 43.56/56 = 0.7779

S = 37.52/32 = 1.1725

Divide by the smallest

Fe = 0.7779/0.7779 = 1

S = 1.1725/0.7779 = 1.5

Multiply through by 2 to express in whole number

Fe = 1 x 2 = 2

S = 1.5 x 2 = 3

Therefore, the empirical formula for the metal sulfide is Fe2S3