Solving a Hydrocarbon Molar Mass Problem

In summary, the conversation discussed finding the molar mass of a hydrocarbon (CxHy) with a carbon percentage of 92.3% and hydrogen percentage of 7.7%. The first equation was found to be 12x=y, and a second equation was needed to solve for the molar mass. The question was raised if the density of the compound to the air could be written as d=(molar mass of the compound)/(molar mass of the water). The conversation ended with the conclusion that the molar mass of the hydrocarbon is 2.69 times higher than the molar mass of the air.
  • #1
mohlam12
154
0
Hey everyone,
I have this problem to solve:

A hydrocarbon (CxHy) contains 92.3% of Carbon and 7.7% of Hydrogen.
1) What is its molar mass, if the density of its smoke to the air is d=2.69 ?

92.3/7.7 = 12
So 12x=y
This is the first equation. I have to find a second one to find what is x and what is y, in order to find the molar mass of CxHy.

Is the density of water to the air can be written as d=(molar mass of the compound)/(molar mass of the water) ?

Anyhelp/hints would be appreciated.
Mohammed
 
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  • #2
mohlam12 said:
1) What is its molar mass, if the density of its smoke to the air is d=2.69 ?

Which are the units of this density, g/dm^3 ?
 
  • #3
Sounds like it is ratio of its density (in gaseous form) to the air density.

"Molar mass" of the air is about 0.78*28+0.21*32+0.01*40 (ie air has density as if it was gas of this molar mass). Hydrocarbon molar mass is 2.69 times higher.
 
  • #4
Got It! Thanks Everyone :)
 
Last edited:

1. What is a hydrocarbon molar mass problem?

A hydrocarbon molar mass problem is a type of calculation used to determine the molar mass of a hydrocarbon compound. This value is important in chemistry as it can be used to determine the amount of substance present in a given sample.

2. How do you solve a hydrocarbon molar mass problem?

To solve a hydrocarbon molar mass problem, you will need to know the chemical formula of the compound and the atomic masses of each element present. Multiply the number of atoms of each element by its atomic mass and then add these values together to get the molar mass of the compound.

3. Why is knowing the molar mass of a hydrocarbon important?

The molar mass of a hydrocarbon is important because it allows us to convert between the mass of a substance and the number of moles present. This is essential for many chemical reactions and calculations, as well as in determining the purity and concentration of a substance.

4. What are some common mistakes when solving a hydrocarbon molar mass problem?

Some common mistakes when solving a hydrocarbon molar mass problem include using the wrong atomic masses, forgetting to account for multiple atoms of the same element, and rounding errors. It is important to double-check all calculations and use accurate values for the atomic masses.

5. Can you use the molar mass of a hydrocarbon to predict its properties?

Yes, the molar mass of a hydrocarbon can provide valuable information about its physical and chemical properties. Generally, the higher the molar mass, the higher the boiling and melting points, as well as the density, of the compound. It can also give insight into its reactivity and solubility in different substances.

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