Air is a mixture of 21% oxygen gas and 79% nitrogen gas. Calculate the average molar mass of a mixture of air. I’m very lost, I thought I was supposed to use mole fraction but it does not get me anywhere, due to not having the total amount of moles. Maybe it has to do with finding pressure?
Here are formulas that I know of:
MM = DRT/P
- MM is molar mass
- D is density
- R is ideal gas constant
- T is temperature in Kelvin
- P is pressure
PV = nRT
- V is volume
- n is moles
Please help, thank you.

Air is a mixture of several gases, where the two most dominant components in dry air are 21 vol% oxygen and 78 vol% nitrogen. Oxygen has a molar mass of 15.9994 g/mol and nitrogen has a molar mass of 14.0067 g/mol. Since both of these elements are diatomic in air - O2 and N2, the molar mass of oxygen gas is aprox.

Explanation:

chemical properties are the characteristic of matter which can only be observed by changing the chemical identity of a sample like flammability reactivity and toxicity.

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