Partial pressure is simply a definition it is the mole fraction of the component in a gas mixture times the total pressure. So if you had a 1% by volume gas mixture of Argon at 100 psi absolute The partial pressure would be one psi. read more
Dalton's Law of Partial Pressure states that the pressure of a gas mixture is the sum of the partial pressures of the individual components of the gas mixture. Simply put, if you have three components, each at a known pressure, then the total pressure is merely the sum of the three. read more
The partial pressure of Argon is determined by the Barometric Pressure and by what percent Argon gas makes up Earth's Atmosphere. Earth's atmosphere is made up of Nitrogen 78.08% (.7808), oxygen 20.95% (.2095), Argon .93% (.0093), and CO2 .03% (.0003). read more