Molecular formula

[Mary]

An organic compound contains C, H, N, and O. Combustion of 0.1023 g of the compound in excess oxygen yielded 0.2766 g of CO₂ and 0.0991 g of H₂O. A sample of 0.4831 g of the compound was analyzed for nitrogen by the Dumas method. At STP, 27.6 mL of dry N₂ was obtained. In a third experiment the density of the compound as a gas was found to be 4.02 g/L at 127 ºC and 256 torr. What are the empirical formula and the molecular formula of the compound?

I started to solve the above problem doing the following steps:
- converted 0.2766 g of CO₂ to x number of moles of CO₂
- converted 0.0991 g of H₂O to y number of moles of H₂O
- substituted x and 2y into the compound CxH₂yNO (since x C atoms go over in front of CO₂, and y/2 atoms go over in front of H₂O in a combustion reaction.

I am not sure what to do next and how to use the information from the rest of the problem to find out the compound empirical and molecular formula.

Thank you,
Mary

[chempass]

An organic compound contains C, H, N, and O. Combustion of 0.1023 g of the compound in excess oxygen yielded 0.2766 g of CO₂ and 0.0991 g of H₂O. A sample of 0.4831 g of the compound was analyzed for nitrogen by the Dumas method. At STP, 27.6 mL of dry N₂ was obtained. In a third experiment the density of the compound as a gas was found to be 4.02 g/L at 127 ºC and 256 torr. What are the empirical formula and the molecular formula of the compound?

I started to solve the above problem doing the following steps:
- converted 0.2766 g of CO₂ to x number of moles of CO₂
- converted 0.0991 g of H₂O to y number of moles of H₂O
- substituted x and 2y into the compound CxH₂yNO (since x C atoms go over in front of CO₂, and y/2 atoms go over in front of H₂O in a combustion reaction.

Thank you,
Mary

Here is the plan how to solve that:
1) From the mass of CO₂ calculate mass percent of C in the compound.
2) From the mass of H₂O calculate mass percent of H in the compound.
3) From the volume of N₂ calculate mass percent of N in the compound.
4) Mass percent of O is 100% minus mass percents of C,H,N.
5) From the density T and P (4.02 g/L at 127 ºC and 256 torr) calculate the molecular weight.
6) Multiply the molecular weight by the (mass percent/100%) for an atom and divide by the atomic weight of this atom to get coefficient in the molecular formula.