1st Year Chemistry Chapter 5 “States and Phases of Matter” Notes 2026 – Complete Guide with Solved Numericals

Class: FSc Part 1 (1st Year) | Subject: Chemistry | Chapter 5: States and Phases of Matter | Punjab Board New Syllabus

Updated 2026: Complete notes for 1st Year Chemistry Chapter 5 “States and Phases of Matter” are available below, covering gases, liquids, and solids in one place, along with every formula and solved numerical needed for the Punjab Board FSc Part 1 exam and MDCAT/ECAT preparation.

Looking for 1st Year Chemistry Chapter 5 Notes?

If you’re searching for FSc Part 1 Chemistry Chapter 5 notes, you’ve landed on the right page. “States and Phases of Matter” follows on from Chapter 4 (Stoichiometry) in the 11th class chemistry book under the new syllabus for all Punjab boards — Lahore, Gujranwala, Multan, Sargodha, Rawalpindi, Faisalabad, DG Khan, Bahawalpur, and Sahiwal — as well as the Federal Board (FBISE). This page brings together gas laws, intermolecular forces, and the classification of solids in one place, so you don’t have to piece together notes from five different websites.

One Chapter, Three States of Matter

This chapter takes a wide-angle view of physical chemistry, covering all three familiar states of matter — gas, liquid, and solid — and explaining what happens at the particle level as a substance moves between them. It combines the numerical, law-based reasoning of gas behaviour with the more conceptual, “why does this happen” explanations behind intermolecular forces and solid structure, making it one of the broadest chapters in FSc Part 1.

Chapter 5 – Topics Covered

Section numbering may vary slightly by edition, but all Punjab boards cover the same core topics listed above.

Key Concepts Explained

Kinetic Molecular Theory and the Three States

Kinetic Molecular Theory (KMT) explains the differences between gases, liquids, and solids in terms of particle spacing, motion, and the strength of intermolecular forces between them. In a gas, particles are far apart, move rapidly and randomly, and have negligible attraction to each other. In a liquid, particles are close together but can still move past one another. In a solid, particles are held in fixed, ordered positions, only vibrating in place. Every gas law in this chapter follows directly from KMT’s assumptions about gas particles specifically.

Boyle’s Law and Charles’s Law

Boyle’s Law states that at constant temperature, pressure and volume of a fixed amount of gas are inversely proportional: P₁V₁ = P₂V₂. Charles’s Law states that at constant pressure, volume is directly proportional to absolute temperature (in kelvin): V₁/T₁ = V₂/T₂. Combined with Avogadro’s Law, these give the general gas equation, PV = nRT, which can solve for any one of pressure, volume, moles, or temperature given the other three.

Dalton’s Law and Graham’s Law

Dalton’s Law of Partial Pressures states that in a mixture of non-reacting gases, the total pressure equals the sum of each gas’s individual partial pressure. Graham’s Law states that the rate of diffusion of a gas is inversely proportional to the square root of its molar mass, which is why lighter gases spread through a room faster than heavier ones.

Liquefaction of Gases

Every real gas can be liquefied if cooled and compressed enough, but only below its critical temperature — the temperature above which pressure alone cannot force it to liquefy. The critical pressure is the minimum pressure needed to liquefy a gas exactly at its critical temperature.

Intermolecular Forces and Hydrogen Bonding

Once a substance condenses into a liquid or solid, intermolecular forces — not the strong covalent or ionic bonds within molecules — determine many of its physical properties. Dipole-dipole forces act between polar molecules, London dispersion forces act between all molecules, and hydrogen bonding (an especially strong dipole-dipole attraction) occurs when hydrogen is bonded directly to nitrogen, oxygen, or fluorine. Hydrogen bonding explains why ice forms an open, hexagonal structure that’s actually less dense than liquid water, which is why ice floats.

Vapor Pressure and Boiling Point

Vapor pressure is the pressure exerted by a vapor in equilibrium with its liquid at a given temperature, and it rises as temperature increases. A liquid boils once its vapor pressure equals the surrounding atmospheric pressure, which is why water boils at a lower temperature at high altitude, where atmospheric pressure is lower.

Classification of Solids

Solids are classified by the type of particle-holding force involved: ionic solids (strong electrostatic attraction between ions, e.g., NaCl), molecular solids (weaker intermolecular forces, e.g., ice), covalent network solids (a continuous network of covalent bonds, e.g., diamond), and metallic solids (a “sea” of delocalized electrons, giving metals their malleability and conductivity). Crystalline solids have a regular, repeating particle arrangement, while amorphous solids lack this long-range order.

Solved Numerical Examples

Example 1 (Boyle’s Law): A gas occupies 4.0 dm³ at 2.0 atm. Find its volume at 4.0 atm, assuming constant temperature.

P₁V₁ = P₂V₂

(2.0)(4.0) = (4.0)(V₂)

V₂ = 8.0 / 4.0 = 2.0 dm³

Example 2 (Charles’s Law): A gas has a volume of 300 cm³ at 27°C. Find its volume at 127°C, at constant pressure.

Convert to kelvin: T₁ = 27 + 273 = 300 K, T₂ = 127 + 273 = 400 K

V₁/T₁ = V₂/T₂

300/300 = V₂/400

V₂ = 400 cm³

Example 3 (Reasoning – Why Ice Floats): Explain why ice is less dense than liquid water.

In ice, hydrogen bonds hold water molecules in a rigid, open hexagonal structure.

This open structure takes up more space per molecule than the less-ordered arrangement in liquid water.

Since the same mass of ice occupies a larger volume than liquid water, ice is less dense and floats.

These are representative examples. Full notes should also include ideal gas equation numericals and Dalton’s/Graham’s Law calculations, which are frequently repeated in board papers.

MCQs, Short Questions & Long Questions

FSc Part 1 Chemistry Chapter 5 is tested across all three question formats in the board exam, blending numerical and conceptual questions in roughly equal measure:

• MCQs: KMT assumptions, gas law definitions, and properties of different solid types
• Short Questions: “Give reason” explanations (why ice floats, why boiling point changes with altitude) or a short 2–3 step gas law calculation
• Long Questions / Numericals: Multi-step gas law problems, or full explanations of hydrogen bonding and its effect on a substance’s properties

Common Mistakes Students Make in Chapter 5

• Using Celsius instead of converting to kelvin before applying Charles’s Law or the general gas equation
• Confusing intermolecular forces (between molecules) with the stronger intramolecular bonds within a molecule
• Assuming all solids behave the same way, without considering whether they’re ionic, molecular, covalent, or metallic
• Explaining boiling point changes with altitude in terms of temperature alone, instead of the underlying vapor pressure relationship

Why This Chapter Matters for MDCAT and ECAT

Because this chapter spans gas law numericals and conceptual reasoning about intermolecular forces, it’s tested from multiple angles in MDCAT and ECAT — quick gas law calculations test numerical fluency, while “why” questions about hydrogen bonding and solid structure test genuine conceptual understanding. Both skill types reappear constantly in later chapters, making this one of the more broadly useful chapters to master early.

Availability for All Boards

These notes are prepared according to the Punjab Board syllabus and are useful for all Punjab boards (Lahore, Gujranwala, Multan, Sargodha, Rawalpindi, Faisalabad, DG Khan, Bahawalpur, Sahiwal), as well as the Federal Board (FBISE) and KPK Board, since Chapter 5 content is broadly consistent across these syllabi.

Download Notes PDF

Click below to view or download the complete Chapter 5 notes in PDF format, including every solved numerical and exercise question.

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Frequently Asked Questions (FAQs)

Q1. Are these Chapter 5 notes free to download?

Yes, all notes on this page are completely free to view and download in PDF format.

Q2. Which board are these notes for?

These notes are prepared according to the Punjab Board syllabus and are useful for all Punjab boards, as well as the Federal Board (FBISE) and KPK Board.

Q3. Why does this chapter cover gases, liquids, and solids together?

The new syllabus groups all three states of matter into a single chapter because they’re best understood by comparison — the same Kinetic Molecular Theory that explains gas behaviour also explains why liquids and solids behave differently, just with much stronger intermolecular forces and much less particle spacing.

Q4. Does this page include solved numericals?

Yes, the notes include fully solved numerical examples covering Boyle’s Law and Charles’s Law, along with reasoning-style questions on intermolecular forces, MCQs, short questions, and long questions.

Q5. How can I download the PDF?

Click the “Download PDF” button above and the notes will open or download directly to your device.

Q6. Are these notes updated for the current syllabus?

Yes, these notes are prepared strictly according to the latest Punjab Textbook Board syllabus for FSc Part 1 Chemistry.

Comments & Feedback

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