Quick question on chemistry notation (mol fraction vs %)

[rwooduk]

Hi,

I have a paper that for a gas mixture writes Ar/25%O₂ implying that 25% of the atmosphere of the gas is oxygen.

I have another paper that writes 0.02 mol frac O₂ for a Ar/CO₂ atmosphere.

Please could someone tell me how I would write the 0.02 mol frac O₂ in the form Ar/X%CO₂ and what X would be and how you got it?

Thanks in advance for any help!

 

[Borek]

How is the molar fraction defined?

 

[rwooduk]

How is the molar fraction defined?

hmm molar fraction is ratio of moles to moles, and to get fraction to percent you would multiply by 100, wow that was easy, sorry, thanks for the direction!

 

[Borek]

Just remember composition of the gas mix - as listed - is ambiguous. 25% O₂ can be v/v (more or less equivalent to molar fraction) or w/w (substantially different).

 

[rwooduk]

Just remember composition of the gas mix - as listed - is ambiguous. 25% O₂ can be v/v (more or less equivalent to molar fraction) or w/w (substantially different).

hmm isn't it exactly equivalent through PV = nRT ?

 

[Borek]

hmm isn't it exactly equivalent through PV = nRT ?

For real gases not so, especially when the ideal gas approximation no longer holds.

 

[rwooduk]

For real gases not so, especially when the ideal gas approximation no longer holds.

Good point, thanks again.