Mastering the concepts of liquid mixtures is vital for scoring high in Physical Chemistry. This solutions chemistry class 12 notes pdf guide provides a structured breakdown of everything from concentration terms to abnormal molar masses. For NEET aspirants, understanding the quantitative relationships in solutions is the gateway to solving complex numericals with speed and precision.
01Introduction to Solutions
A solution is a homogeneous mixture of two or more chemically non-reacting substances whose composition can be varied within certain limits. In a binary solution, we deal with two components: the Solute (present in smaller quantity) and the Solvent (present in larger quantity).
Classification based on Physical State
| Type of Solution | Solute | Solvent | Common Example |
|---|---|---|---|
| Gaseous Solution | Gas | Gas | Mixture of oxygen and nitrogen (Air) |
| Liquid Solution | Solid | Liquid | Sugar dissolved in water |
| Solid Solution | Gas | Solid | Solution of hydrogen in palladium |
02Concentration Terms and Calculations
Quantifying the amount of solute in a solution is the foundation of this solutions chemistry class 12 notes pdf. Various terms are used depending on whether mass or volume is being considered.
Mole Fraction (χ)
It is the ratio of the number of moles of one component to the total number of moles of all components in the solution. For a binary mixture of A and B:
03Solubility and Henry’s Law
Solubility is the maximum amount of a solute that can be dissolved in a specific amount of solvent at a specific temperature. For gases in liquids, pressure plays a defining role, described by Henry’s Law.
Applications of Henry’s Law
- Soft Drinks: CO2 is sealed under high pressure to increase its solubility.
- Scuba Diving: To avoid ‘bends’ caused by nitrogen bubbles, divers use tanks diluted with helium.
- Anoxia: At high altitudes, low partial pressure of oxygen leads to low blood oxygen levels.
04Vapour Pressure and Raoult’s Law
Vapour pressure is the pressure exerted by vapours in equilibrium with the liquid at a particular temperature. This solutions chemistry class 12 notes pdf section covers the behavior of volatile and non-volatile solutes.
05Ideal and Non-Ideal Solutions: Deviations
When the interactions between solute and solvent (A-B) are different from pure components, we see deviations. This is a high-yield topic in our solutions chemistry class 12 notes pdf guide.
| Characteristic | Positive Deviation | Negative Deviation |
|---|---|---|
| A-B Interactions | Weaker than A-A or B-B | Stronger than A-A or B-B |
| Vapour Pressure | Higher than expected | Lower than expected |
| ΔHmixing | Positive (Endothermic) | Negative (Exothermic) |
| Example | Ethanol + Acetone | Chloroform + Acetone |
06Colligative Properties
Colligative properties depend only on the number of solute particles and not on their nature. These are the most important numerical areas in the solutions chemistry class 12 notes pdf.
1. Relative Lowering of Vapour Pressure
2. Elevation of Boiling Point
3. Depression of Freezing Point
07Osmotic Pressure and Reverse Osmosis
Osmosis is the spontaneous flow of solvent through a semi-permeable membrane. Osmotic pressure (π) is the minimum pressure required to stop this flow.
08Van’t Hoff Factor (i) and Abnormal Molar Mass
When solutes associate or dissociate in a solvent, the number of particles changes, leading to “abnormal” molar masses. The van’t Hoff factor (i) corrects this in our solutions chemistry class 12 notes pdf formulas.
- Dissociation (e.g., NaCl): i > 1. Molar mass appears lower.
- Association (e.g., Acetic acid in benzene): i < 1. Molar mass appears higher.
Quick Revision Summary
- Solutions are homogeneous mixtures; binary has 2 components.
- Molarity depends on T; Molality is independent of T.
- Henry’s Law: P = KHχ. Solubility of gas ∝ Pressure.
- Ideal solutions: ΔHmix = 0, ΔVmix = 0.
- Azeotropes are constant boiling mixtures that cannot be separated by distillation.
- Colligative properties depend on the *number* of particles only.
- ΔTb and ΔTf use molality (m).
- π = CRT uses molarity (C).
- Van’t Hoff factor i > 1 for dissociation; i < 1 for association.
- Reverse Osmosis is used for water purification and desalination.
09Frequently Asked Questions
Why is molality preferred over molarity for experimental work?
What are azeotropes?
How does adding a non-volatile solute affect boiling point?
What is the physical significance of the van’t Hoff factor?
Why is osmotic pressure used to determine molar mass of polymers?
Perfect Your NEET Score with KSquare
Ready to dissolve your doubts? Join KSquare Institute’s Mission 180 Rankers Batch and master Physical Chemistry with personalized mentorship and high-yield study resources.
Table of Contents
Chemistry — Class 12
| 01 | Solutions | Go to page |
| 02 | Electrochemistry | Go to page |
| 03 | Chemical Kinetics | Go to page |
| 04 | d- and f-Block Elements | Go to page |
| 05 | Coordination Compounds | Go to page |
| 06 | Haloalkanes and Haloarenes | Go to page |
| 07 | Alcohols, Phenols and Ethers | Go to page |
| 08 | Aldehydes, Ketones and Carboxylic Acids | Go to page |
| 09 | Amines | Go to page |
| 10 | Biomolecules | Go to page |