Use Dalton’s law: partial pressure of a gas = mole fraction of the gas × total pressure
Formula: (P_i = X_i times P_{total})
Find the mole fraction: (X_i = frac{n_i}{n_{total}})
Calculate the total moles of all gases in the mixture
Divide the moles of the target gas by the total moles to get its mole fraction
Multiply the mole fraction by the total pressure to get the partial pressure
If using ideal gas law, calculate directly with (P = frac{nRT}{V})
For a gas in a mixture, use (P_i = frac{n_iRT}{V})
Ensure pressure units are consistent before calculating
Common pressure units include atm, kPa, mmHg, and Pa