Finding molecular formula from combustion of organic compound A

[nineteen]

Homework Statement

In an organic compound "A" only C,H and O is present. 1.22g of A is completely burned and it gives 0.84g of CO₂ and 0.54g of H₂O. If the relative molecular mass of "A" is 123. Find the molecular formula of A.
[/B]
I have showed my attempt at solving this problem, but I think it is wrong. Please help me out here. After what I have done last, there are only a few more steps to find the empirical formula and then the molecular formula itself, but I think what I have done is wrong. Please try and correct me, I'd appreciate it a lot.

2. Homework Equations

no. of moles = Mass/Molar mass
n of the molecular formula = Molar mass/ Formula mass of the empirical formula

(I guess that those are the only equations)​

The Attempt at a Solution

[/B]
Mass of C in CO₂ produced: (12/44) x 0.84g = 0.22g
Mass of O in CO₂ produced: (32/44) x 0.84g = 0.61g

Mass of H in H₂O produced: (2/18) x 0.54g = 0.06g
Mass of O in H₂O produced : (16/18) x 0.54g = 0.48g

Total masses;
C = 0.22g
O = 1.09g
H = 0.06g

Molar ratios of elements;

C ----> (0.22/12) = 0.01
H ----> (0.06/1) = 0.06
O ----> (1.09/16) = 0.06

Dividing all by the smallest value;

C ----> 0.01/0.01 = 1
H ----> 0.06/0.01 = 6
O ----> 0.06/0.01 = 6

 

[BvU]

Hi 19,

Molar ratios of elements

in what ? In A ?

 

[nineteen]

Hi 19,

in what ? In A ?

Yes, the elements C,H and O...
By all means, I don't know whether this approach to the solution is correct or not.

 

[BvU]

It is not. Your elements add up to 1.38 g. There is only 1.22 g of A

 

[nineteen]

It is not. Your elements add up to 1.38 g. There is only 1.22 g of A

Yeah that's what. Can you please help me find the solution to this?

 

[BvU]

Write the stoeciometric equation for the reaction $C_xO_yH_z + ?? O_2 \rightarrow ?? CO_2 + ?? H_2O$
Three unknowns, so you need to find three equations.

 

[nineteen]

Write the stoeciometric equation for the reaction $C_xO_yH_z + ?? O_2 \rightarrow ?? CO_2 + ?? H_2O$
Three unknowns, so you need to find three equations.

Isn't there any other method to solve this, except for the stoichiometry method?

 

[BvU]

You'll need it, I'm afraid. Express the ?? in terms of $x, y$ and $z$

 

[nineteen]

You'll need it, I'm afraid. Express the ?? in terms of $x, y$ and $z$

Thank you very much!

 

[mjc123]

The numbers here make no sense. Apart from anything else, an organic compound containing only C, H and O cannot have an odd RMM. Check that you've copied all the numbers correctly; if you have, I suspect a mistake in the question.

 

[nineteen]

The numbers here make no sense. Apart from anything else, an organic compound containing only C, H and O cannot have an odd RMM. Check that you've copied all the numbers correctly; if you have, I suspect a mistake in the question.

Ok friend, I'll look into it.