# Homework Help: Stoichiometry Help

1. Jun 26, 2006

### bubbles

Hi. I need help on a stoichiometry problem:

When a particular hydrocarbon was burned in air, 0.467g of CO, 0.733g of CO2, and .450g of H2O were formed.

The question asks me to find the empirical formula of the hydrocarbon and the number of grams of O2 used in the reaction. The answers are C2H3(empirical formula) and 1.19g of O2, but I don't understand how to get the answers.

So far, I tried to find the empirical formula by finding out the number of moles of each compound. I got .017 mol Co, .017 mol CO2, and .025 mol water. So using this information, I was able to get a chemical equation of
$$Unknown Hydrocarbon + 9O_2 \rightarrow 4CO + 4CO_2 + 6H_2O$$
But I don't know how to get the empirical formula from that.

Is this the correct step to take? Or should I try something else? Thanks.

Last edited: Jun 26, 2006
2. Jun 27, 2006

### ultima9999

The first thing you should do is find the amount of moles of each component in the hydrocarbon. You have the moles for CO, CO2 and H20, now you can find the moles of each component (C, H).

3. Jun 27, 2006

### bubbles

Thank you, Ultima9999.

4. Jul 4, 2006

### vijay123

this problem is relatively tough...did you get the ans. or do you need help?

5. Jul 4, 2006

### bubbles

I got the answer after finding the mol of each element (I forgot to do that before!). Yeah, this problem was a tough one and took me a while to solve.