Question

A sample of a compound containing only carbon and hydrogen was burned and produced 3.42 g of H2O and 6.69 g of CO2. The measured molar mass of the unknown compound is 58.1 g/mol. Determine the molecular formula of the compound.

Answer 1

It's been a while since I have done one of these but I like setting up a generic chemical equation because you know you are going to get all your hydrogen from the amount of water you are going to produce and all your carbon from the CO2

Answer 2

\[C_xH_xO_x -> CO_2 + H_2O\]

Answer 3

The question says that the compound only contains carbon and hydrogen

Answer 4

So its CxHy > CO2+ H2O

Answer 5

well it was burned with o2 in the chamber so it would be CxHx +O2 -> H20 + CO2

Answer 6

Now just convert from mass of h20 to moles, to moles of H and plug in in for x and do the same for CO2 and you should end up with the compund

Answer 7

I dont understand how to do that I have the moles of H2O but how do I find moles of Hydrogen from this?

Answer 8

\[3.42 gramsH_2O (\frac{1 mole H_2O}{18.02 g H_2O})(\frac{2 mole H^+}{1 mole H_2O})=\] multiply across and you get your answer.

Answer 9

Where do you get 2 moles of H+ how do you know that the ratio of moles of H2O to H+ is 1:2?

Answer 10

because when you Look at H_2O there is 2 h+ atoms and 1 O -2 atoms

Answer 11

or you can write the formation equation \[H_2O \rightarrow 2 H^+ + O^-2\]

Answer 12

So for CO2: C its 1:1?

Answer 13

yes unless you are looking at the O

Answer 14

ok wait let me see if i can solve thanks so far