Why is partial pressure important?

is important due to its many applications.For example:

1- Some gases are collected over water in the laboratory. The gas during collection gathers water vapors and becomes moist. The pressure exerted by this moist gas is , therefore, the sum of partial pressure of dry gas and that of water vapors. The partial pressure exerted by water vapors is called aqueous tension.

Pmoist = Pdry + Pw.vap Pmoist = Pdry + aqueous tension Pdry = Pmoist - aqueous tension

While solving the numericals the aqueous tension is subtracted from total pressure(Pmoist).

2-The process of respiration depends upon difference in partial pressures. When animals inhale air, oxygen moves into the lungs as partial pressure of oxygen in air is 159 torr while the partial pressure of oxygen in lungs is 116 torr.Similarly, carbon dioxide moves out of lungs as its partial pressure is more in the lungs than in air.