Topics Covered
10 key topics in this chapter
Study Resources
Key Concepts
01. What is Matter?
Anything that has mass and occupies space is called matter. Matter is made up of tiny particles — atoms and molecules — that are in constant random motion.
02. States of Matter
Matter exists in three common states: solid (fixed shape & volume), liquid (fixed volume, takes shape of container), and gas (no fixed shape or volume). A fourth state — plasma — exists at extreme temperatures.
03. Interconversion of States
Heating a solid causes melting (fusion), and heating a liquid causes vaporisation. Cooling reverses these. Sublimation is the direct solid-to-gas conversion (e.g., camphor, dry ice).
04. Latent Heat
During a change of state, temperature remains constant even though heat is being absorbed or released. This hidden heat is called latent heat (latent heat of fusion / vaporisation).
05. Evaporation
Evaporation is a surface phenomenon that occurs at all temperatures below boiling point. Rate increases with temperature, surface area, wind speed, and decreases with humidity. It causes cooling.
06. Diffusion
Particles spontaneously mix due to their kinetic energy. Diffusion is fastest in gases, slower in liquids, and negligible in solids. Rate increases with temperature.
Formulas at a Glance
| # | Name | Expression | Notes |
|---|---|---|---|
| 01 | Melting Point of Ice | 0 °C = 273 K |
Temperature at which ice melts |
| 02 | Boiling Point of Water | 100 °C = 373 K |
Temperature at which water boils |
| 03 | Celsius ↔ Kelvin | T(K) = T(°C) + 273 |
Temperature conversion |
| 04 | Latent Heat of Fusion | L_f = 334 J/g (water) |
Heat to melt 1 g of ice at 0 °C |
| 05 | Latent Heat of Vaporisation | L_v = 2260 J/g (water) |
Heat to vaporise 1 g of water at 100 °C |
Important Notes
Exam Tips & Common Mistakes
Always convert temperature to Kelvin before using gas-law formulas.
State the correct SI unit for temperature: Kelvin (K). Celsius is common but not SI.
Latent heat questions often ask "Why does ice at 0 °C cool a drink more than water at 0 °C?" — latent heat is the answer.
Diffusion rate order: Gas > Liquid > Solid. This is a one-mark recall question every year.
Distinguish between evaporation (cool, surface) and boiling (hot, bulk) clearly in 3-mark answers.