Example of positive deviation and its causes
Example:
Benzene and ethanol mixture
Explanation of benzene-ethanol intermolecular forces
Negative Deviation
Definition of negative deviation
Explanation of intermolecular forces
Example of negative deviation and its causes
Example:
Acetone and chloroform mixture
Explanation of acetone-chloroform intermolecular forces
Colligative Properties
Definition of colligative properties
Explanation of how they depend on the number of particles
Brief mention of four colligative properties:
Vapour pressure lowering
Boiling point elevation
Freezing point depression
Osmotic pressure
Vapour Pressure Lowering
Explanation of how solutes lower the vapour pressure of solvents
Explanation of vapor pressure lowering equation
Example of calculating the decrease in vapour pressure
Example:
Solvent: Water
Solute: NaCl
Initial vapour pressure of water: 25 mmHg
Calculate the final vapour pressure with the addition of NaCl
Boiling Point Elevation
Explanation of how solutes elevate the boiling point of solvents
Explanation of boiling point elevation equation
Example of calculating the increase in boiling point
Example:
Solvent: Water
Solute: NaCl
Initial boiling point of water: 100°C
Calculate the final boiling point with the addition of NaCl
Problems with Solution - Vapour Pressure of Solutions of Solids in Liquids
Example problem:
A solution is prepared by dissolving 5 grams of glucose (C6H12O6) in 200 grams of water. The vapour pressure of pure water is 23.8 mmHg at a certain temperature. Calculate the vapour pressure of the solution assuming ideal behaviour.
Solution:
Calculate the mole fraction of glucose: Xglucose = moles of glucose / total moles
Calculate the moles of glucose: moles = mass / molar mass
Calculate the moles of water: moles = mass / molar mass
Calculate the total moles: moles of glucose + moles of water
Calculate the vapour pressure using Raoult’s Law equation: P1 = X1 * P0
Substitute values to find the solution’s vapour pressure
Answer: The vapour pressure of the solution is X mmHg.
Problems with Solution - Non-Ideal Solutions
Example problem:
A solution is prepared by mixing 20 mL of methanol (CH3OH) with 30 mL of ethanol (C2H5OH). The vapour pressure of pure methanol is 93.0 mmHg and the vapour pressure of pure ethanol is 44.0 mmHg at the same temperature. Calculate the vapour pressure of the solution assuming ideal behaviour.
Solution:
Calculate the mole fraction of methanol: Xmethanol = moles of methanol / total moles
Calculate the moles of methanol: moles = volume * density / molar mass
Calculate the moles of ethanol: moles = volume * density / molar mass
Calculate the total moles: moles of methanol + moles of ethanol
Calculate the vapour pressure using Raoult’s Law equation: P1 = X1 * P0
Substitute values to find the solution’s vapour pressure
Answer: The vapour pressure of the solution is X mmHg.
Colligative Properties - Freezing Point Depression
Explanation of how solutes affect the freezing point of solvents
Explanation of freezing point depression equation
Example of calculating the decrease in freezing point
Example:
Solvent: Water
Solute: Sodium chloride (NaCl)
Initial freezing point of water: 0°C
Calculate the final freezing point with the addition of NaCl
Answer: The freezing point of the solution is X°C.
Colligative Properties - Osmotic Pressure
Explanation of osmotic pressure and its importance in biological systems
Explanation of how solutes affect osmotic pressure
Explanation of the van’t Hoff equation for osmotic pressure: π = iMRT
π: Osmotic pressure
i: Van’t Hoff factor (number of particles per formula unit)
M: Molarity of the solute
R: Gas constant
T: Temperature in Kelvin
Osmotic Pressure Calculation
Example problem:
A solution is prepared by dissolving 0.5 moles of glucose (C6H12O6) in 2 liters of water at 25°C. Calculate the osmotic pressure of the solution.
Solution:
Calculate the van’t Hoff factor (i) for glucose
Calculate the molarity of the solution: Molarity = moles of solute / volume of solution
Convert temperature to Kelvin: T(Kelvin) = 25 + 273
Substitute values into the van’t Hoff equation to calculate osmotic pressure
Answer: The osmotic pressure of the solution is X atm.
Problems with Solution - Vapour Pressure Lowering
Example problem:
A solution is prepared using 10 grams of sucrose (C12H22O11) in 500 mL of water. The vapour pressure of pure water is 23.8 mmHg at a certain temperature. Calculate the vapour pressure of the solution assuming ideal behaviour.
Solution:
Calculate the mole fraction of sucrose: Xsucrose = moles of sucrose / total moles
Calculate the moles of sucrose: moles = mass / molar mass
Calculate the moles of water: moles = volume * density / molar mass
Calculate the total moles: moles of sucrose + moles of water
Calculate the vapour pressure using Raoult’s Law equation: P1 = X1 * P0
Substitute values to find the solution’s vapour pressure
Answer: The vapour pressure of the solution is X mmHg.
Colligative Properties - Boiling Point Elevation
Explanation of how solutes affect the boiling point of solvents
Explanation of boiling point elevation equation
Example of calculating the increase in boiling point
Example:
Solvent: Water
Solute: Sodium chloride (NaCl)
Initial boiling point of water: 100°C
Calculate the final boiling point with the addition of NaCl
Answer: The boiling point of the solution is X°C.
Colligative Properties - Reverse Osmosis
Explanation of reverse osmosis and its applications
Difference between osmosis and reverse osmosis
Explanation of pressure required for reverse osmosis
Example of reverse osmosis in water purification
Applications of Colligative Properties
Introduction to various applications of colligative properties in everyday life and industries
Mention of applications such as antifreeze, food preservation, inkjet printing, and more
Brief explanation of how each application utilizes the colligative properties
Summary and Conclusion
Recap of key concepts covered in the lecture:
Raoult’s Law and ideal solutions
Positive and negative deviations from Raoult’s Law
Vapour pressure lowering
Boiling point elevation
Freezing point depression
Osmotic pressure
Reverse osmosis
Importance of understanding these concepts in chemistry and related fields
Encouragement for further exploration and study in the topic
Applications of Colligative Properties - Antifreeze
Explanation of how antifreeze works
Antifreeze lowers the freezing point of the coolant in a car’s radiator
This prevents the coolant from freezing in cold temperatures and damaging the engine
Example: Ethylene glycol used as antifreeze in automobiles
Applications of Colligative Properties - Food Preservation
Explanation of how colligative properties are used in food preservation
Addition of solutes (such as salt or sugar) to foods lowers the water activity, inhibiting microbial growth
Explanation of the process of osmosis in food preservation
Example: Canning, salting, and sugaring methods
Applications of Colligative Properties - Inkjet Printing
Explanation of how colligative properties are used in inkjet printing
The ink used in inkjet printers has a specific viscosity and surface tension to ensure printing accuracy
Addition of solutes or adjusting the solvent composition alters the colligative properties of the ink
Example: Glycol, glycerol, and surfactants used in ink formulations
Applications of Colligative Properties - Osmotic Pressure in Biology
Explanation of how osmotic pressure is crucial for biological systems
Cells maintain osmotic balance through osmosis
Osmotic pressure helps in water uptake, nutrient absorption, and waste removal in cells
Example: Plant cells taking up water from the soil through osmosis
Applications of Colligative Properties - Reverse Osmosis in Water Purification
Explanation of reverse osmosis as a water purification process
High pressure is applied to force water molecules through a semipermeable membrane, leaving impurities behind
Reverse osmosis removes contaminants such as salts, bacteria, and organic matter from water
Example: Desalination of seawater to obtain freshwater
Summary and Conclusion
Recap of key concepts covered in the lecture:
Vapour pressure of solutions of solids in liquids
Raoult’s Law and ideal solutions
Positive and negative deviations from Raoult’s Law
Colligative properties: vapour pressure lowering, boiling point elevation, freezing point depression, osmotic pressure, reverse osmosis
Applications of colligative properties in various fields
Emphasis on the importance of understanding these concepts for 12th Boards exam and beyond
Encouragement for further practice and exploration in the topic
Vapour Pressure of Solutions of Solids in Liquids Introduction to the topic Definition of vapour pressure Explanation of solutions of solids in liquids