Final answer:
The partial pressure of oxygen is proportional to its concentration, determined by Dalton's law. The partial pressure is calculated by multiplying the mole fraction of oxygen (21% in air) by the total pressure of the gas mixture.
Step-by-step explanation:
The partial pressure of oxygen is proportional to the oxygen concentration in a gas mixture. This relationship is described by Dalton's law of partial pressures, which states that the partial pressure of a gas is equal to the total pressure of the gas mixture multiplied by the mole fraction of that gas. In this equation, the partial pressure of oxygen (PA) would be PA = XA * Pt, where XA is the mole fraction of oxygen and Pt is the total pressure of the gas mixture.
At standard atmospheric pressure, the partial pressure of oxygen can be calculated using the mole fraction of oxygen in air (approximately 21%), thus PA = (0.21)(1.00 atm) = 0.21 atm. The mole fraction is a unit of concentration defined as the number of moles of a component of a solution divided by the total number of moles of all components.