1. Gas Mixtures Chapter 13

2. Composition of a Gas Mixture: Mass and Mole Fractions Mass Fraction (mf): The ratio of mass of a component to the mass of the mixture is called the mass fraction. Mole Fraction (y): The ratio of the mole number of a component to the mole number of the mixture is called the mole fraction.

3. The mass of a substance can be expressed in terms of the mole number N and molar mass M of the substance as The molar mass and the Gas constant of a mixture can be expressed as

4. P-v-T Behavior of Gas Mixtures Is based on: Dalton’s Law of additive Pressures Amagat’s Law of additive Volumes

5. Dalton’s Law of additive Pressures The pressure of a gas mixture is equal to the sum of the pressures each gas would exert if it existed alone at the mixture temperature and volume

6. Amagat’s Law of additive Volume The volume of a gas mixture is equal to the sum of the volume each gas would occupy if it existed alone at the mixture temperature and pressure

7. P-v-T Behavior of Ideal Gas Mixtures For ideal gases,the above two laws are identical and give identical results. P i is called the component pressure and V i the component volume. The ratio P i /P m is called the pressure fraction and the ratio V i /V m is called the volume fraction of component i.

8. Ideal Gas Mixtures Partial Pressure: The quantity y i P m is called the partial pressure Partial Volume: The quantity y i V m is called the partial volume For ideal gas mixture, the mole fraction, the pressure fraction and the volume fraction of a component are identical

9. Real Gas Mixtures For real gases Dalton’s Law of additive Pressures and Amagat’s Law of additive Volumes can be used with reasonable accuracy. The components pressures and volumes need to be evaluated using more exact equations of state. Other ways is to use : 1.Compressibility factors 2.Kay’s Rule

17. Properties of Gas Mixtures The extensive properties of a gas mixture, can be determined by summing the contributions of each component of the mixture. The intensive properties of a gas mixture, involve averaging in terms of mass or mole fractions.

20. Properties of Gas Mixtures SEE EXAMPLES 12.3-12.5 (TEXT)