[Jov4nTh3Yu9o]

I have tried many times to solve this, and I keep getting the wrong answer. IDK why.

1. A compound contains only carbon, hydrogen, and oxygen. Combustion of 45.04 g of the compound yields 66.02 g of CO2 and 27.02 g of H2O.
The molar mass of the compound is 180.156 g/mol.

*Each part of this problem should be submitted separately to avoid losing your work*
A. Calculate the grams of carbon (C) in 45.04 g of the compound: 
B. Calculate the grams of hydrogen (H) in 45.04 g of the compound.
C. Calculate the grams of oxygen (O) in 45.04 g of the compound.

A.For this I take 66.02/44.01 to find moles of C which=1.5 Then I take 1.5x12.011 to find part A
B. I take 27.02/18.008 to find moles of H which=3 then take 3x1.008 to find B
C. I just take A+B then subtract that from 180.156 for part C.

Did I miss a step in my stoich?

2.
Based on your previous answers, calculate

1. the moles of carbon (C) in 45.04 g of the compound:   
2. the moles of hydrogen (H) in 45.04 g of the compound:
3. the moles of oxygen (O) in 45.04 g of the compound:

For this I just put the moles I found when calculating the grams C=1.5 H=3 O=1.7

But this is wrong too and I can't figure out why.

[fledarmus]

C. I just take A+B then subtract that from 180.156 for part C.

Keep track of your units! A is in grams, B is in grams, why would you subtract from 180.156 g/mol?

What should you be subtracting it from?

Without getting 1 right, you can't get 2 right.

[Jov4nTh3Yu9o]

Its the total mass of the compound.. But I tried just subtracting the mass of H2O from 2H (2.016) to find O and it is still wrong.

[Borek]

Its the total mass of the compound.

It is not. It is a molar mass, you are not told you have 1 mole of the substance.

[fledarmus]

Its the total mass of the compound.

It is not. It is a molar mass, you are not told you have 1 mole of the substance.

You are, however told what the total mass of the compound is. Reread the question and substitute the proper number...