Solutions Formulas - Chemistry Class 12

Learn important formulas from the Solutions chapter of Class 12 Chemistry with examples, variables and applications.

📐 Solutions Formulas

Complete collection of formulas with explanations and examples

Depression in Freezing Point

$$Delta T_f = K_f m$$

Description: Depression in Freezing Point is a standard relation used in solutions.

Example:

Apply the relation: Delta T_f = K_f m

Identify the known values, substitute them in the relation, and solve for the unknown quantity.
Result depends on the substituted values.

Applications:

  • Use this when the quantities in the relation are known and the missing quantity is required.
  • Exam relevance: jee-main, jee-advanced, cuet, neet

Elevation in Boiling Point

$$Delta T_b = K_b m$$

Description: Elevation in Boiling Point is a standard relation used in solutions.

Example:

Apply the relation: Delta T_b = K_b m

Identify the known values, substitute them in the relation, and solve for the unknown quantity.
Result depends on the substituted values.

Applications:

  • Use this when the quantities in the relation are known and the missing quantity is required.
  • Exam relevance: jee-main, jee-advanced, cuet, neet

Molality

$$m = moles of solute / mass of solvent in kg$$

Description: Molality is a standard relation used in solutions.

Example:

Apply the relation: m = moles of solute / mass of solvent in kg

Identify the known values, substitute them in the relation, and solve for the unknown quantity.
Result depends on the substituted values.

Applications:

  • Use this when the quantities in the relation are known and the missing quantity is required.
  • Exam relevance: jee-main, jee-advanced, cuet, neet

Molarity

$$M = moles of solute / volume of solution in litre$$

Description: Molarity is a standard relation used in solutions.

Example:

Apply the relation: M = moles of solute / volume of solution in litre

Identify the known values, substitute them in the relation, and solve for the unknown quantity.
Result depends on the substituted values.

Applications:

  • Use this when the quantities in the relation are known and the missing quantity is required.
  • Exam relevance: jee-main, jee-advanced, cuet, neet

Mole Fraction

$$x_i = n_i / sum n_i$$

Description: Mole Fraction is a standard relation used in solutions.

Example:

Apply the relation: x_i = n_i / sum n_i

Identify the known values, substitute them in the relation, and solve for the unknown quantity.
Result depends on the substituted values.

Applications:

  • Use this when the quantities in the relation are known and the missing quantity is required.
  • Exam relevance: jee-main, jee-advanced, cuet, neet

Osmotic Pressure

$$pi = CRT$$

Description: Osmotic Pressure is a standard relation used in solutions.

Example:

Apply the relation: pi = CRT

Identify the known values, substitute them in the relation, and solve for the unknown quantity.
Result depends on the substituted values.

Applications:

  • Use this when the quantities in the relation are known and the missing quantity is required.
  • Exam relevance: jee-main, jee-advanced, cuet, neet

Raoult Law

$$p_i = x_i p_i^0$$

Description: Raoult Law is a standard relation used in solutions.

Example:

Apply the relation: p_i = x_i p_i^0

Identify the known values, substitute them in the relation, and solve for the unknown quantity.
Result depends on the substituted values.

Applications:

  • Use this when the quantities in the relation are known and the missing quantity is required.
  • Exam relevance: jee-main, jee-advanced, cuet, neet

Van Hoff Factor

$$i = observed colligative property / normal colligative property$$

Description: Van Hoff Factor is a standard relation used in solutions.

Example:

Apply the relation: i = observed colligative property / normal colligative property

Identify the known values, substitute them in the relation, and solve for the unknown quantity.
Result depends on the substituted values.

Applications:

  • Use this when the quantities in the relation are known and the missing quantity is required.
  • Exam relevance: jee-main, jee-advanced, cuet, neet

Quick Reference

Depression in Freezing Point: $Delta T_f = K_f m$
Elevation in Boiling Point: $Delta T_b = K_b m$
Molality: $m = moles of solute / mass of solvent in kg$
Molarity: $M = moles of solute / volume of solution in litre$
Mole Fraction: $x_i = n_i / sum n_i$
Osmotic Pressure: $pi = CRT$
Raoult Law: $p_i = x_i p_i^0$
Van Hoff Factor: $i = observed colligative property / normal colligative property$

💡 Worked Examples

Step-by-step solutions using Solutions formulas

Example 1: Area of Circle

Circle Area Formula
Problem:

Find the area of a circle with radius 7 cm.

Solution:
  1. Given: r = 7 cm
  2. Apply formula: A = πr²
  3. Substitute: A = π × 7²
  4. Calculate: A = π × 49 = 49π cm²
  5. Approximate: A ≈ 49 × 3.14159 ≈ 153.94 cm²
Answer:

Area = 49π cm² ≈ 153.94 cm²

🎯 Practice Problems

Try these problems to test your understanding:

Practice Problem 1

Solve the quadratic equation: x² - 7x + 12 = 0

Practice Problem 2

Find the area of a circle with diameter 14 cm.

Practice Problems

Check Your Formula Recall

Write each formula once, define every variable, then solve one direct substitution problem before moving to mixed questions.

Apply Solutions

Pick two formulas from this page and create your own values for the variables. Verify units and signs before calculating.

Derivation Notes

Focus on how the formula is built, not only the final expression. Derivations help with board-exam reasoning and multi-step application questions.

  • Start from the definition or identity used in the chapter.
  • Write assumptions clearly before substituting values.
  • Track units through each step to catch calculation mistakes.

Where These Formulas Are Used

Board Exam Problems

Use these formulas for direct numerical questions, proof-based steps, and short-answer reasoning in Chemistry.

Competitive Practice

Memorize the condition of use for each formula so you can identify the right expression quickly under timed practice.

Related Formula Chapters

Biomolecules 1 formulas Chemical Kinetics 4 formulas Coordination Compounds 1 formulas Electrochemistry 4 formulas Solutions 8 formulas

These Solutions formulas help students revise concepts quickly and apply equations accurately in exam-style problems.

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