𝐁𝐢𝐡𝐚𝐫 𝐁𝐨𝐚𝐫𝐝 𝐂𝐥𝐚𝐬𝐬 𝟏𝟐 𝐂𝐡𝐞𝐦𝐢𝐬𝐭𝐫𝐲 𝐂𝐡 - 𝟐 𝐒𝐨𝐥𝐮𝐭𝐢𝐨𝐧 𝐎𝐧𝐞 𝐒𝐡𝐨𝐭 | 𝐎𝐛𝐣𝐞𝐜𝐭𝐢𝐯𝐞 + 𝐒𝐮𝐛𝐣𝐞𝐜𝐭𝐢𝐯𝐞 + 𝐏𝐘𝐐𝐬 𝐢𝐧 𝟏 𝐕𝐢𝐝𝐞𝐨

𝐁𝐢𝐡𝐚𝐫 𝐁𝐨𝐚𝐫𝐝 𝐂𝐥𝐚𝐬𝐬 𝟏𝟐 𝐂𝐡𝐞𝐦𝐢𝐬𝐭𝐫𝐲 𝐂𝐡 - 𝟐 𝐒𝐨𝐥𝐮𝐭𝐢𝐨𝐧 𝐎𝐧𝐞 𝐒𝐡𝐨𝐭 | 𝐎𝐛𝐣𝐞𝐜𝐭𝐢𝐯𝐞 + 𝐒𝐮𝐛𝐣𝐞𝐜𝐭𝐢𝐯𝐞 + 𝐏𝐘𝐐𝐬 𝐢𝐧 𝟏 𝐕𝐢𝐝𝐞𝐨 - Notes

1. Summary

This video provides a one-shot revision of the Solution chapter from the Class 12 Chemistry syllabus for the Bihar Board (English Medium). The video covers the chapter's theoretical concepts, including objective and subjective questions, important PYQs, exam-oriented short notes, and explanations based on the 2026 board exam pattern. The video emphasizes key concepts, properties of solutions, and important definitions that can be useful for exams.

2. Key Takeaways

* The video focuses on the Solution chapter, covering theoretical concepts, objective and subjective questions, and PYQs.

* Solutions are defined as homogeneous mixtures, with key components being solvent (major amount) and solute (minor amount).

* Concentration terms like mass percentage, volume percentage, molarity, and molality are discussed.

* Henry's Law, relating gas solubility to pressure, and its implications are explained.

* Types of solutions based on physical states.

* The video offers tips and tricks for the exam and highlights important definitions to remember for board exams.

3. Detailed Notes

#### **I. Introduction & Overview (0:00:00 - 0:00:48)**

* Introduction to the video and the chapter, emphasizing its usefulness for the Class 12 Science students.

* The video content: Objective questions, Subjective questions, Important PYQs, Exam Oriented Short Notes and 2026 Board Pattern Based Explanation.

* Emphasis on liking, sharing, and commenting to suggest the next chapter.

* Recap of the previous chapter (Solid State).

* The importance of the chapter for exam preparation.

#### **II. Solutions and Homogeneous Mixtures (0:00:48 - 0:03:19)**

* Definition of Solution: Homogeneous mixtures of two or more components.

* Daily life examples: Tea.

* Explanation of Homogeneous vs. Heterogeneous Mixtures.

* Water as an example of a solution, the example of NaCl + Water.

* Example of heterogeneous mixtures like oil + water.

* Properties of Homogeneous mixtures (uniform composition) vs. heterogeneous mixtures (non uniform composition, different phases).

#### **III. Components of a Solution (0:03:19 - 0:03:50)**

* Components of Solution: Solvent and Solute

* *Solvent*: Component present in major amount

* *Solute*: Component present in minor amount.

* *Alternative definition*: Solute dissolve in Solvent.

#### **IV. Types of Solutions (0:03:50 - 0:04:47)**

* Types of solution based on the number of components

* Binaray solution: Two components

* Ternary Solution: Three components

* *Note:* More than three components are also possible.

* Types of Solutions Based on Physical State: Example- gas + gas (air), liquid + gas, gas + liquid, solid + gas and solid + solid.

#### **V. Concentration Terms (0:10:39 - 0:16:08)**

* The concept and the importance of Concentration Terms (needed to determine the amount of solute in different amount of solvent)

* Mass Percentage = (Mass of solute / Mass of solution) \* 100

* Volume percentage = (Volume of component / Volume of solution) \* 100

* Mole fraction is the ratio of number of moles of solute to total number of moles.

* Important: Mole Fraction is Unitless.

* For binary solutions, XA + XB = 1 (sum of all mole fractions in a solution equals 1).

* Molarity (M) = (Moles of solute / Volume of solution in liters)

* Molarity.

* Moles = Given weight / Molecular weight.

#### **VI. Solving a Molarity Problem (0:16:08 - 0:22:33)**

* *Question:* Calculate the molarity of sugar solution.

* Use of formula and solving by identifying given information and calculating the required information.

* C12H22O11

* *Solution:* (0.1 moles sugar)/ (234.2 gm) * 1000 / 100 = 0.5 M

#### **VII. Molality and Difference between Molarity and Molality (0:16:28 - 0:19:46)**

* Molality (m) = (Moles of solute / Weight of solvent in kg) (small 'm' is used to represent Molality).

* Molarity (M) - Number of moles of Solute / Volume of Solution (in Liters).

* Units.

* Molarity is temperature-dependent (volume changes with temperature).

* Molality is independent of temperature (weight of solvent remains constant).

#### **VIII. Types of Solutions (0:19:57 - 0:22:33)**

* *Question:* Determine the molarity of a solution made by dissolving 2 gm of NaOH in 200 mL of solution.

* Solving the Problem.

* Finding Moles: Given weight / Molecular weight.

* Using formula: Find Molarity.

* Answer: =0.25 M

#### **IX. Henry's Law (0:22:33 - 0:26:05)**

* Definition of concentration in general. Number of moles of solute to liters of solution.

* What is Henry's Law?

* *Definition:* It explains the solubility of a gas in a liquid.

* The statement of the law: At a constant temperature, the solubility of a gas in a liquid is directly proportional to the partial pressure of the gas above the solution.

* Henry’s Law Equation.

* *P (Partial pressure of gas) = KH (Henry's law constant) \* X (Mole fraction of gas)*

#### **X. Examples and Application of Henry's Law (0:26:05 - 0:30:45)**

* Soda water bottle example.

* The increased pressure and decreased pressure when opening the soda water bottle.

* Oxygen Cylinder example.

#### **XI. Key points about Henry’s law (0:30:45 - 0:32:48)**

* Application: In the production of carbonated beverages (e.g., sodas) to increase the solubility of CO2.

* Dalton's Law and Application.

#### **XII. Factors Affecting Solubility of a Gas (0:32:48 - 0:33:56)**

* Factors affecting solubility.

* Nature of solute and solvent.

* Pressure on the gas.

* The higher the KH value the less the solubility will be.

* At a higher temperature solubility decreases.

#### **XIII. Dissolution and Crystallization (0:33:56 - 0:36:03)**

* When a solid solute is added to the solvent.

* Dissolution is when the solute is dissolved in solvent

* When is the rate of dissolution and the rate of crystallization be equal.

#### **XIV. Saturated and Unsaturated Solutions (0:36:03 - 0:47:00)**

* Saturation.

* At constant temperature, max amount of solute is added, that is saturation of a solution.

* Hypertonix solution when higher concentration is used

* Types of solutions.

#### **XV. Raoult's Law (0:47:00 - 0:50:39)**

* This explains the vapor pressure of solutions containing non-volatile solutes.

* *Raoult's law for a volatile solvent:*

* P solution = P°solvent \* Xsolvent

* Where:

* P solution is the vapor pressure of the solution.

* P°solvent is the vapor pressure of the pure solvent.

* Xsolvent is the mole fraction of the solvent in the solution.

#### **XVI. Raoult's Law (0:50:39 - 0:52:37)**

* Relative Lowering of Vapor Pressure (RLVP):

* (P°solvent - Psolution)/P°solvent = Xsolute

* P°A is the vapour pressure.

* Pa and PB will be total pressure when two liquids get mixed.

#### **XVII. Positive and Negative Deviations (0:52:37 - 0:56:59)**

* If the intermolecular forces of attraction between the solute-solvent are weaker than those in the pure components, then it is a positive deviation.

* P(total) > P A + P B , bond strength less

* If the intermolecular forces of attraction between the solute-solvent are stronger than those in the pure components, then it is a negative deviation.

* P(total) < P A + P B, with the bond stronger.

* Graph of Positive and Negative Deviations.

#### **XVIII. Factors Affecting Solubility (0:59:59 - 0:59:59)**

* The factors are.

* The Nature of the Solute and Solvent: “Like dissolves like.” (Polar solutes dissolve in polar solvents, and nonpolar solutes dissolve in nonpolar solvents).

* Temperature: The effect of temperature on solubility.

* Pressure: Usually, pressure has a negligible effect on the solubility of solids and liquids.

#### **XIX. Colligative Properties (01:11:04 - 01:17:29)**

* Colligative Properties: Those properties of a solution that depend only on the number of solute particles in a solution, not on the nature of the solute particles.

#### **XX. Relative Lowering of Vapor Pressure (RLVP) (01:17:29 - 01:24:46)**

* Lowering of Vapor Pressure: P°solvent - P solution

* RLVP= (P°solvent - Psolution) / P°solvent = X solute

* RLVP is the difference in vapor pressure.

* P = CRT. C is the concentration.

* The properties for a better learning in chemistry.

* Higher the amount of solutes.

* Purity of the solution.

* Molarity can change.

#### **XXI. Elevation of Boiling Point (01:24:46 - 01:30:55)**

* *Boiling Point:* The temperature at which the vapor pressure of a liquid equals the atmospheric pressure.

* Delta Tb = kb * m

* *kb:* Elevation point constant (ebullioscopic constant).

* Units: K kg/mol.

* *m:* Molality.

* Boiling point will be higher for a higher pressure.

* How do you find the degree of freezing.

#### **XXII. Freezing Point Depression (01:30:55 - 01:31:53)**

* *Freezing Point:* Freezing point of a solution is lower than the freezing point of the pure solvent.

* Delta Tf = Kf \* m

* *Tf* (Freezing Point) = Kf ( Cryoscopic constant) \* m (Molality)

#### **XXIII. Osmosis and Osmotic Pressure (01:31:53 - 01:33:21)**

* Definition, examples, and components.

#### **XXIV. Vant Hoff factor (01:33:21 - 01:35:50)**

* Van’t Hoff factor - Ratio of total number of moles after association or dissociation to the total number of moles initially.