Physical Chemistry

1
Physical Chemistry
2
Chapter OneIntroduction 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- Boyles 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 Boyles 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 Vc Va
• (Vb Va) (Vc Vb )
• 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
• The pressure exerted on the gas by the piston
  equals the pressure exerted on the piston by the
  gas.
• 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
  dont depend on the size of the system.
• PV' nRT
• Where

17
Thank You