Determine the empirical formulas for compounds with the following percent compositions:
(a)15.8% carbon and 84.2 percent sulfur
(b)40.0 percent carbon, 6.7% hydrogen, and 53.3% oxygen

a)  

b)

Explanation:

a) If percentage are given then we are taking total mass is 100 grams.

So, the mass of each element is equal to the percentage given.

Mass of C = 15.8g

Mass of S= 84.2 g

Step 1 : convert given masses into moles.

Moles of C =

Moles of S=

Step 2 : For the mole ratio, divide each value of moles by the smallest number of moles calculated.

For C =

For S =

The ratio of C  : S = 1:2

Hence the empirical formula is

b) Mass of C= 40 g

Mass of H= 6.7 g

Mass of O = 53.3 g

Step 1 : convert given masses into moles.

Moles of C =

Moles of H =

Moles of O =

Step 2 : For the mole ratio, divide each value of moles by the smallest number of moles calculated.

For C =

For H =

For O =

The ratio of C : H: O= 1 :2: 1

Hence the empirical formula is