[gabz]

if 5.8g of a particular hydrocarbon burns to give 9 g of water, determine the empirical formula of the hydrocarbon.

PLEASE HEEELLLLP!!!! thx

[Dan]

1. Which atoms is a hydrocarbon made up of? And what is the general chemical equation for the combustion of a hydrocarbon?

ie. Hydrocarbon + _________ -------> water + _______

2. Water is formed. Water is H₂O, so where id the O come from and where did the H come from?

3. If you know the mass of water formed, you can work out how many moles of H atoms are present in the 9 g of water you formed. What does this tell you about the number of moles of H atoms in the 5.8 g of your hydrocarbon?

4. Now that you know how many moles of H are in 5.8 g of your hydrocarbon, you can calculate the mass of that hydrogen. You now know how much of that 5.8 g is due to the mass of hydrogen present. The mass left over is due to a different element, which one? So how many moles of that element are present?

5. The ratio of the moles of hydrogen (question 3), and the moles of the other element (question 4) will give you your empirical formula.


Note: Usually you would start with a balanced equation in question 1, however in this case it would be a little more complicated since you are not given any information about the structure of the hydrocarbon, like degree saturation, or whether it's cyclic, so I have avoided this approach for this question.