Help How to get the mole fraction ?

In summary, the conversation is about calculating the mole fraction of ethylene glycol in an aqueous antifreeze solution. The solution is 37.0% ethylene glycol by mass and has a density of 1.047 g/cm3. The mole fraction equation is given and the molar masses of ethylene glycol and water are noted. The result obtained by the person asking for help is 13.8%, but it is wrong. After checking, they realize it should be 14.6%, but the system does not accept percentages.
  • #1
zhen
48
0
An aqueous antifreeze solution is 37.0% ethylene glycol (C2H6O2) by mass. The density of the solution is 1.047 g/cm3.

Q: Calculate the mole fraction of ethylene glycol.

I tried it many time, but still got the wrong answer.

that is what i did:

mole fraction:(X) = nA/(nA+nB)
set the mass of the solution - m
molar mass of C2H6O2: 62
molar mass of H2O: 18 --- (I think the solvent should be H2O...but not quite sure)

=> [(0.37 * m)/62]/[(0.37 * m/62 + 0.63 * m/18)]
= 13.8%------but that is wrong

need help...please
 
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  • #2
Check your math - equation is OK, just the result is wrong.
 
  • #4
oh...never mind...
the system does not accept percentage...
 

What is mole fraction and why is it important?

Mole fraction is a way to express the concentration of a particular component in a mixture. It is the ratio of the number of moles of that component to the total number of moles in the mixture. It is important because it provides a standardized way to measure the amount of a substance in a mixture and allows for easy comparison between different mixtures.

How do you calculate mole fraction?

Mole fraction can be calculated by dividing the number of moles of a particular component by the total number of moles in the mixture. The formula is X = n1/nt, where X is the mole fraction, n1 is the number of moles of the component, and nt is the total number of moles in the mixture.

What are some common units for mole fraction?

The most common units for mole fraction are mol/mol or mol%. These represent the number of moles of a particular component per 100 moles of the mixture. However, mole fraction can also be expressed in other units such as parts per million (ppm) or parts per billion (ppb).

How is mole fraction used in chemistry?

Mole fraction is used in various calculations in chemistry, such as determining the partial pressure of a gas in a mixture using Dalton's law or calculating the concentration of a solute in a solution. It is also used to express the composition of a mixture in a more precise and standardized way.

Can mole fraction be greater than 1?

Yes, mole fraction can be greater than 1. This occurs when the number of moles of a particular component is greater than the total number of moles in the mixture. It is possible for a component to have a higher concentration than the total concentration of all other components in the mixture.

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