Equilibrium in a system containing I2 and I

[Kaushik]

Summary:: .

Consider a container consisting of I2 and I in equilibrium.
I2 <-> 2I (Is there any to write chemical equations here?)
Will both of them separately contribute to the total pressure (as partial pressures)?
If no, why?
If yes, should we use mole fraction or volume composition to calculate individual contribution? I thought mole fraction was the right approach but unfortunately, in this case, it did not yield the answer.

 

[chemisttree]

Doesn’t work like it used to...
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[Borek]

Will both of them separately contribute to the total pressure (as partial pressures)?

Yes.

If yes, should we use mole fraction or volume composition to calculate individual contribution?

Most likely many ways to skin that cat, mole fraction should work OK.

I thought mole fraction was the right approach but unfortunately, in this case, it did not yield the answer.

Hard to comment not knowing what was the question, what was the answer given as a correct one, what you did nor what was the answer you got.

 

[Kaushik]

Hard to comment not knowing what was the question, what was the answer given as a correct one, what you did nor what was the answer you got.

I think I just figured out the mistake. I took the ratio stoichiometric coefficients instead of the mole fraction.
Using $PV = nRT$ we can show that taking volume composition is the same as taking a mole fraction.

Yeah btw, one more question. Taking stoichiometric coefficients is same as taking mole fraction if and only if the reaction is of the form $n(aA + bB -> cC + dD)$. Isn't it? Like mole of A is 'na', B is 'nb' and so on...So can we conclude it by saying that taking mole fraction is the same as stoichiometric coefficients if and only if there is no reactant left and everything is reacted completely (no limiting reagent)?
(it might be confusing...I couldn't express it properly. Hopefully, you will understand)

 

[Borek]

Not sure what you mean. Molar fraction is number of moles of the substance over total number of moles of all substances involved. In some cases it can be calculated with the help of stoichiometry, but that's not necessary - molar fraction of oxygen in the air is quite easy to calculate even if it doesn't react with any other atmosphere components.