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Chemistry Forums for Students => High School Chemistry Forum => Topic started by: Wanderlusion on June 03, 2019, 10:51:29 AM

Title: Ideal gas equation
Post by: Wanderlusion on June 03, 2019, 10:51:29 AM

Hi, I am new here and have my exams coming up!

I understand simple PV = nRT questions when they’re to do with just one gas or finding the moles of gases produced but I’m confused by what n actually means. I know it’s ‘number of moles’ but moles of what? Is it always referring to total number of moles of gases reacting or does it’s usage depend on the question?

 I get confused with questions when there are multiple gases reacting and I’m asked to find the volume or pressure of just one gas produced.

Any help appreciated, thanks :)

Title: Re: Ideal gas equation
Post by: Corribus on June 03, 2019, 01:42:41 PM

In the ideal gas approximation, gasses are treated as non-reacting and identical, so it doesn't matter if it's a single gas in a container or a mixture of gasses. n in either case is the total number of moles of gas. Because the partial pressures are additive, you can also treat each gas separately. The implication is that the partial pressure of the gas, for a mixture of ideal gasses, scales with the respective mole fraction.