An unknown hydrocarbon compound was analyzed for hydrogen by elemental
analysis and results show that it contains 5.611% H. What is the empirical
formula?

The answer to your question is    C₁.₄H₁

Explanation:

Data

Percent of H = 5.611%

Percent of C = 100 - 5.611

                     = 94.389 %

Empirical formula = ?

Process

1.- Express the percents as mass

Hydrogen = 5.611 g

Carbon = 94.389 g

2.- Convert the grams to moles

Hydrogen

                         1 g 1 mol

                      5.611 g x

                         x = (5.611 x 1) / 1

                             x = 5.611 moles

Carbon

                      12 g 1 mol

                     94.389 g  x

                         x = (94.389 x 1) / 12

                         x = 7.866 moles

3.- Divide by the lowest number of moles

Hydrogen    5.611 / 5.611 = 1

Carbon         7.866 / 5.611 = 1.4

4.- Write the empirical formula

                             C₁.₄H₁