What is Raoult’s Law?
The mole fraction of the solute component is directly proportional to its partial pressure
What are the two types of liquid-liquid solutions based on Raoult’s Law?
- Ideal Solutions
- Non-Ideal Solutions
What defines an Ideal Solution?
Solutions that obey Raoult’s Law at every range of concentration and at all temperatures
What is required for a solution to be considered ideal?
Intermolecular forces of attraction between A – A, B – B, and A – B must be nearly equal
List the characteristics of Ideal Solutions
- They follow Raoult’s Law
- Δmix H = 0
- Δmix V = 0
- Solute-solute interaction is similar to solvent-solvent interaction
What does Δmix H = 0 signify in Ideal Solutions?
No heat is released or absorbed during mixing
What does Δmix V = 0 indicate in Ideal Solutions?
Total volume of solution is the same as the sum of the volume of solute and solvent
Give examples of Ideal Solutions
- n-hexane and n-heptane
- Bromoethane and Chloroethane
- Benzene and Toluene
- CCl4 and SiCl4
- Chlorobenzene and Bromobenzene
- Ethyl Bromide and Ethyl Iodide
- n-Butyl Chloride and n-Butyl Bromide
What defines a Non-Ideal Solution?
Solutions that don’t obey Raoult’s Law at every range of concentration and at all temperatures
List the characteristics of Non-Ideal Solutions
- Different solute-solute and solvent-solvent interactions compared to solute-solvent interactions
- Δmix H ≠ 0
- Δmix V ≠ 0
What is the significance of Δmix H ≠ 0 in Non-Ideal Solutions?
Heat may be released or absorbed during mixing
What are the two types of Non-Ideal Solutions?
- Positive deviation from Raoult’s Law
- Negative deviation from Raoult’s Law
What is meant by Positive Deviation from Raoult’s Law?
Vapour pressure of the component is greater than expected
List the conditions for Positive Deviation from Raoult’s Law
- PA > PA0 xA
- PB > PB0 xB
- A – B < A – A or B – B
- Δmix H > 0
- Δmix V > 0
Give examples of solutions showing Positive Deviation from Raoult’s Law
- Acetone and Carbon disulphide
- Acetone and Benzene
- Carbon Tetrachloride and Toluene
- Methyl Alcohol and Water
- Acetone and Ethanol
- Ethanol and Water
What is meant by Negative Deviation from Raoult’s Law?
Total vapour pressure is less than expected
List the conditions for Negative Deviation from Raoult’s Law
- PA < PA0 xA
- PB < PB0 xB
- A – B > A – A or B – B
- Δmix H < 0
- Δmix V < 0
Give examples of solutions showing Negative Deviation from Raoult’s Law
- Chloroform and Benzene
- Chloroform and Diether
- Acetone and Aniline
- Nitric Acid (HNO3) and water
- Acetic Acid and pyridine
- Hydrochloric Acid (HCl) and water
