Atomic Fractions: Calculating Xc & Xo in H2, H2O & CO2

In summary, the conversation is about determining the atomic fractions of carbon and oxygen in a gas composition at room temperature. The question is asked and it is suggested that the partial pressures of each substance at room temperature need to be calculated in order to determine the atomic fractions. There is uncertainty about how to do this and the conversation ends with one person suggesting an answer and thanking the other for their help.
  • #1
jamesdawson19
2
0
Hi Guys,

I have a bit of a problem with some course work please help:

The question is: Determine the atomic fractions Xc and Xo (carbon and oxygen) for the following gas composition at room temperature:
50% H2, 30% H2O, 20% CO2

I am sure you need to work out the partial pressures for each of the substances at room temp and then determine how much carbon/oxygen will be present, however i have no idea how to do this

Please help

Much appreciated.
 
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  • #2
jamesdawson19 said:
The question is: Determine the atomic fractions Xc and Xo (carbon and oxygen) for the following gas composition at room temperature:
50% H2, 30% H2O, 20% CO2

If those are number percentages (rather than mass percentages) then a particular sample of the mixture might have:

50 H2 molecules
30 H2O molecules
20 CO2 molecules

If this sample were to be dissociated into its component atoms and they were binned and counted, how would that look?
 
  • #3
Hi Gneill,

That is the answer than i am going with H:O:C = 16:7:2 so O = 28% and C is 8%

Thanks for your help
 

1. What is an atomic fraction?

An atomic fraction is the ratio of the number of atoms of a specific element in a molecule to the total number of atoms in that molecule. It is typically expressed as a decimal or percentage.

2. How do you calculate atomic fractions?

To calculate atomic fractions, you need to know the molecular formula of the compound and the atomic weight of each element in the compound. Then, you can use the formula Xn = (n x M)/Mtotal, where Xn is the atomic fraction of a specific element, n is the number of atoms of that element in the molecule, and Mtotal is the total molecular weight of the compound.

3. What is Xc and Xo in the context of atomic fractions?

Xc and Xo are the atomic fractions of carbon and oxygen, respectively. These values represent the percentage of carbon and oxygen atoms in a compound, relative to all other atoms in that compound.

4. How do you calculate Xc and Xo in H2, H2O, and CO2?

In H2, there is 1 carbon atom and 0 oxygen atoms, so Xc = (1 x 12.01)/(2 x 1.01 + 1 x 12.01) = 0.8571 or 85.71% and Xo = (0 x 16.00)/(2 x 1.01 + 1 x 12.01) = 0%.

In H2O, there is 0 carbon atoms and 2 oxygen atoms, so Xc = (0 x 12.01)/(2 x 1.01 + 1 x 16.00) = 0% and Xo = (2 x 16.00)/(2 x 1.01 + 1 x 16.00) = 0.9333 or 93.33%.

In CO2, there is 1 carbon atom and 2 oxygen atoms, so Xc = (1 x 12.01)/(1 x 12.01 + 2 x 16.00) = 0.2727 or 27.27% and Xo = (2 x 16.00)/(1 x 12.01 + 2 x 16.00) = 0.5455 or 54.55%.

5. Why is it important to calculate atomic fractions?

Calculating atomic fractions can provide valuable information about the composition of a compound. It can also help in understanding the chemical and physical properties of a substance, as well as its reactivity and behavior in different environments.

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