Dalton's law of partial pressures and mixture properties.
Dalton: P=ΣP_i and P_i=y_iP. Amagat: V=ΣV_i. Mixture properties: M=Σy_iM_i, c_p=Σm f_i c_p,i. Moist air treated as mixture of dry air and vapour. Used for combustion products, exhausts and humid air.
Air is about 21% O₂ and 79% N₂ by mole; O₂ partial pressure at 1 atm is 21.3 kPa.
Dalton's law lets you handle gas mixtures such as air or exhaust, because each component acts as if it occupied the volume alone.
Dalton's law of partial pressures and mixture properties.
Dalton's law lets you handle gas mixtures such as air or exhaust, because each component acts as if it occupied the volume alone.
The total pressure of a mixture equals the sum of the partial pressures of its components at the same temperature and volume.
Divide the number of moles of a component by the total number of moles, which also equals its partial pressure over the total pressure.
Typical applications include finding the partial pressure of oxygen in a breathing gas mixture, calculating the composition of an exhaust gas for emissions monitoring and estimating the properties of humid air from its water vapour partial pressure.
Study "Internal combustion engine performance" first (topic 41 of 105 in Thermodynamics & Fluids). It covers the groundwork this topic builds on.
Mole fraction vs mass fraction. Partial pressure of water vapour. Entropy of mixing.
Air is about 21% O₂ and 79% N₂ by mole; O₂ partial pressure at 1 atm is 21.3 kPa.
The next topic is "Chemical equilibrium", which builds directly on this one.
It is classed as Intermediate in Thermodynamics & Fluids (topic 42 of 105). It is an intermediate topic. Work through the beginner topics in Thermodynamics & Fluids first.
Want to practise? Open the interactive course for quick checks, quizzes, simulations and progress tracking.