Chemistry · Class 11 · Some Basic Concepts in Chemistry

Mole Concept and Stoichiometry for JEE

Everything you need for this topic on one page: the ideas, the formulas, the traps, and free lectures that explain it well.

Last updated: 26 October 2026

Direct answer

The base of all physical chemistry: moles, molar mass, empirical and molecular formulas, limiting reagent, concentration terms and equivalent concepts.

Key ideas

Mole Concept and Stoichiometry: what you must understand

1 mole = 6.022 × 10²³ particles
The limiting reagent is used up first and fixes the product amount
Molarity changes with temperature; molality does not
Balance the equation before any calculation

Formula sheet

Must-know formulas for Mole Concept and Stoichiometry

n = mass / molar mass = N / Nₐ
Molarity M = moles of solute / litres of solution
Molality m = moles of solute / kg of solvent
Mole fraction χ = nᵢ / n_total

One-page formula sheet

Printable Mole Concept and Stoichiometry formula sheet: formulas, key ideas and traps on one page. Save it as a PDF for offline revision.

Avoid

Common mistakes students make

Using volume of solvent instead of solution for molarity
Not converting mL to L
Skipping the limiting reagent check

For the exam

How this topic is asked in JEE

Appears frequently. Weak mole concept causes mistakes in every physical chemistry chapter. Fix it first.

NCERT map

Where Mole Concept and Stoichiometry is in NCERT

Chapter names follow the current rationalised NCERT textbooks. Read these sections before solving PYQs.

Class	Book	Chapter	Sections JEE asks from
Class 11	Chemistry Part I	Some Basic Concepts of Chemistry	Atomic and Molecular Masses; Mole Concept and Molar Masses; Percentage Composition; Stoichiometry and Stoichiometric Calculations; Reactions in Solutions

JEE Advanced level

A JEE Advanced-level example on Mole Concept and Stoichiometry

Question. A mixture of anhydrous Na2CO3 and NaHCO3 weighing 22.1 g is heated strongly until constant mass is reached. The residue weighs 15.9 g. This residue is then dissolved in water and treated with excess dilute HCl. Find (a) the mass of each component in the original mixture, and (b) the volume of CO2 evolved at STP when the residue reacts with HCl. (Molar masses: Na2CO3 = 106, NaHCO3 = 84)

Show solution

On heating, Na2CO3 is stable but NaHCO3 decomposes: 2NaHCO3 → Na2CO3 + H2O + CO2. Let mass of Na2CO3 = a g and NaHCO3 = b g.
From the reaction, b g of NaHCO3 gives (106/168) × b = (53b/84) g of Na2CO3. So residue mass = a + 53b/84.
Setting up equations: a + b = 22.1 and a + 53b/84 = 15.9. Subtracting gives 31b/84 = 6.2, so b = 16.8 g (NaHCO3) and a = 5.3 g (Na2CO3).
Total Na2CO3 in residue = original 5.3 g + formed from NaHCO3 = 5.3 + 10.6 = 15.9 g = 0.15 mol.
Residue reacts: Na2CO3 + 2HCl → 2NaCl + H2O + CO2. Moles of CO2 = 0.15 mol. Volume at STP = 0.15 × 22.4 = 3.36 L.

Answer: (a) Na2CO3 = 5.3 g, NaHCO3 = 16.8 g; (b) Volume of CO2 at STP = 3.36 L

This example was solved twice independently and both solutions agree.

Free lectures

Best free lectures for Mole Concept and Stoichiometry

Full-chapter free lectures picked from YouTube search results by views, from established JEE channels (mostly in Hinglish). Use the subtopic list to jump straight to the part you need (timestamps come from each video's own chapter list). Watch one, then solve PYQs the same day.

Manzil 2026: MOLE CONCEPT in 1 Shot: All Concepts & PYQs Covered | JEE Main & Advanced — JEE Wallah, 7:54:16
Jump to a subtopic (33)
- 00:00 Introduction
- 07:18 Matter
- 21:50 Plasma
- 28:35 Chemical Classification of Matter
- 57:58 Atom & Molecules (With Types)
- 01:09:42 Representation of an Element
- 01:15:00 Cations and Anions
- 01:21:22 Formula of a Salt
- 01:24:54 Isotopes, Isobars, Isotones & Isodiaphers
- 01:39:50 Dalton Atomic Theory
- 01:49:47 Laws of Chemical Combination (Definite Proportion, Multiple Proportion, Conservation of Ma
- 02:34:38 Gay Lussac's Law of Combining Volumes
- 02:46:58 Relative Atomic Mass
- 02:54:00 Atomic Mass & Molecular Mass
- 03:05:38 Valence Electrons
- 03:14:04 Mole
- 03:28:42 Gram Atomic or Gram Molecular Weight
- 03:39:58 Avagadro's Hypothesis
- 03:47:12 Y - Map
- 03:55:58 Questions
- 04:36:20 Percentage Composition
- 04:46:12 Questions
- 05:32:16 Empirical Formula
- 05:36:30 Questions
- 05:50:00 Average Atomic Mass
- 05:57:18 Average Molecular Weight
- 06:05:20 Density
- 06:22:48 Stoichiometry
- 06:27:17 Questions
- 07:03:25 Limiting Reagent (Questions)
- 07:18:40 Sequential Reaction (Questions)
- 07:25:44 Percentage Yield (Questions)
- 07:52:25 Thank you
Mole Concept in ONE SHOT | All Concepts & PYQs Covered | Basic to Advanced | Class 11 JEE — PW JEE, 10:37:53
Jump to a subtopic (17)
- 00:00 Introduction
- 03:08 Matter and Non-matter
- 14:18 Plasma and Bose-Einstein condensate
- 17:10 Classification of Matter
- 58:12 Atomicity of molecules
- 01:04:52 Representation of an atom
- 01:32:05 Isotopes and Isobars
- 01:54:25 Dalton Atomic Theory
- 04:04:18 Avogadro's Hypothesis
- 04:21:35 Questions
- 06:08:28 Average Atomic Mass
- 06:30:26 Density
- 06:52:34 Stoichiometry
- 07:28:05 Limiting Teagent 08:43:42 Concentration Terms
- 09:29:52 Questions and PYQs
- 10:00:38 Percentage Concentration Terms
- 10:39:50 Thank you

Practise

Where to practise for free

11 JEE Main 2026 PYQs on Mole Concept and Stoichiometry, with solutions.
Read the chapter in NCERT textbooks (official, free), then solve its NCERT Exemplar (official, free) questions.
Chapter-wise past questions: JEE Main and Advanced PYQs and question bank.
Timed practice tests: NTA Abhyas practice tests (official, free) and our free mock tests.
See it move: interactive simulation.

FAQs

Frequently asked questions

Is Mole Concept and Stoichiometry important for JEE Main 2027?

Appears frequently. It is part of the official 'Some Basic Concepts in Chemistry' unit in the JEE Main 2027 syllabus.

What are the most important formulas in Mole Concept and Stoichiometry?

n = mass / molar mass = N / Nₐ; Molarity M = moles of solute / litres of solution; Molality m = moles of solute / kg of solvent.

How should I study Mole Concept and Stoichiometry for JEE?

Understand the key ideas from NCERT or one full lecture, learn the formula sheet, then solve 25–30 past JEE questions on the topic. Weak mole concept causes mistakes in every physical chemistry chapter. Fix it first.