1. Physical Chemistry

2. Chapter One Introduction and definition of terms

3. Contents Introduction The concept of state The equation of state of an ideal gas Simple equilibrium Extensive and intensive properties

4. 1. Introduction What is meant by physical chemistry? It is concerned with the study of matter and energy and the relationship between them.

5. 2. The concept of state State means the knowledge of mass, velocity, position and all modes of motion of that system. a) The microscopic state of system: It is the state of atoms, molecules and ions. b) The macroscopic state of system: It is the state of the whole object or system. For example a piece of iron.

6. 3.The equation of state of an ideal gas 1- Boyle’s law: It is a pressure –volume relationship of a gas at constant temperature.

7. 3.The equation of state of an ideal gas 2- Charles’ law: It is a volume-temperature relationship of a gas at constant pressure.

8. 3.The equation of state of an ideal gas Combination of Boyle’s law and charles’ law yields: Where P ° = standard pressure ( 1 atm) T ° = standard temperature ( 0 ° C) V(T,P) = volume at temperature T and pressure P

9. 3.The equation of state of an ideal gas Then the constant equals 0.082057 lit.atm/degree.mole This constant is termed R, the Gas Constant and being applicable to all gases.

10. Example Consider a system at fixed P & T then according to the equation of state of an ideal gas, the sate of that system is fixed. So consider the volume of the system to be V = f(P,T)

11. Example Consider a process which moves the system an infinitesimal distance from state a to state c dV = V c – V a = (V b – V a ) + (V c – V b ) Where a →b occurs at constant temperature While b→c occurs at constant pressure

12. Note:

13. Example

14. Example Consider the path a →d→c Thus the volume is a state function

15. 4. Simple equilibrium The system is at rest, i.e., is at equilibrium, when: 1. The pressure exerted on the gas by the piston equals the pressure exerted on the piston by the gas. 2. The temperature of the gas equals the temperature of the surroundings. (provided that the cylinder material is a conductor of heat).

16. 5. Extensive and intensive properties Properties ( or state variables) are classified into 2 types: 1- Extensive properties: They are the properties which their magnitudes depend on the size of the system. 2- Intensive properties: They are the properties which their magnitudes don’t depend on the size of the system. PV ' = nRT Where

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