Question

What are the partial pressure in milibars of oxygen and nitrogen in dry mixture of 21% o2 and 79% n2 at 1 atm?

Answer 1

You can easily calculate the partial pressure of oxygen keeping in mind the definition of partial pressure.

First of all You have the find out the mole fraction of the oxygen and we know that mole fraction can be calculated from percentage composition of the gas divided by the total percentage of all gases 

So here oxygen is 21% = mole fraction of 21 % oxygen =21/100 = 0.21 

Here total pressure is give which is =750mm of Hg 

Partial pressure of oxygen will be = 750 *0.21  = 157.5 mm of Hg .

So partial pressure of oxygen will be 157.5 mmHg