Question

The mass percentage composition of dry air at sea level is approximately N2: 75.5; O2: 23.2; Ar:1.3. What are the partial pressure of each component when the total pressure is 1 atm

Answer 1

Moles of Nitrogen:

N2 (N=14 X 2= 28) = 75.5 / 28 =2.696

Moles of Oxygen

O2 (O=16X2= 32) = 23.2 / 32 = 0.725

Moles of Argon

Ar (Ar =40 X1 = 40) = 1.3 / 40 = 0.0325

Total moles = 3.453

Partia pressure of Nitogen:

Moles N₂ / total moles = partial pressure N₂ / total pressure
2.696 / 3.453 = x / 1 (x = partial pressure)

=0.7807 atm

Partia pressure of oxygen:

Moles O₂ / total moles = partial pressure O₂ / total pressure
0.725 / 3.453 = x / 1  (x = partial pressure)

=0.2099 atm

Partia pressure of Argon:
Moles Ar / total moles = partial pressure Ar / total pressure
0.0325 / 3.45 = x / 1  (x = partial pressure)

= 0.00942 atm

(Note: we can mix all partial partial pressure will come 1.00 atm)