A34.0 gram sample of an un-known hydrocarbon is burned in excess oxygen to form 93.5 grams of carbon dioxide and 76.5 grams of water. what is a possible molecular formula of the hydro-carbon?

The answer to your question is  CH₄

Explanation:

Process

1.- Write the possible chemical reaction

                   CxHy + O₂   ⇒    CO₂  +   H₂O

2.- Calculate the amount of carbon in the reaction

Molecular mass of CO₂ = 12 + 32 = 44 g

                         44 g of CO₂ 12 g of carbon

                         93.5 g of CO₂  x

                          x = (93.5 x 12) / 44

                          x = 25.5 g of carbon

3.- Calculate the mass of hydrogen in the sample

Molecular mass of water = 2 + 16 = 18 g

                         18 g of water   2 g of hydrogen

                          76.5 g of water    x g of hydrogen

                           x = (76.5 x 2) / 18

                           x = 8.5 g of hydrogen

4.- Calculate the moles of carbon and hydrogen in the sample

                           12g of carbon 1 mol

                           25.5g of carbon x

                             x = (25.5 x 1) / 12

                              x = 2.12 moles of carbon

                            1 g of hydrogen 1 mol

                            8.5 g of hydrogen x

                             x = (8.5 x 1) / 1

                             x = 8.5 moles of hydrogen

5.- Divide both number of moles by the lowest number

carbon = 2.12 / 2.12 = 1

hydrogen = 2.12 = 8,5 / 2.12 = 4

6.- Write the molecular formula

                                                    CH₄                                        

the answer would be c