Intensive vs Extensive Properties
Quick Answer
Intensive properties do not depend on how much substance you have. Extensive properties do.
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What Each One Really Means
This one is foundational, and it appears in almost every introductory chemistry lab report. So let me settle it clearly. An intensive property does not depend on how much of the substance you have. Density is the classic example. A single drop of water has the same density as an entire ocean. Same with boiling point, melting point, colour, and temperature. These properties are intrinsic to the substance itself. An extensive property does depend on the amount you have. Mass, volume, and total enthalpy are the classic examples. A bucket of water has more mass than a cup of water. Same substance, different amount, different value. Now why does this matter? When you do calculations in thermodynamics, you often convert extensive properties into intensive ones by dividing by mass or moles. That is how we get specific heat capacity, molar volume, and so on. This lets us compare substances fairly, regardless of sample size. A common exam trap is asking whether a property changes if you cut a sample in half. If the property is intensive, the answer is no. If it is extensive, the answer is yes, it halves. Density, boiling point, colour: no change. Mass, volume, heat capacity: they change. That is the test. Memorise the list and you will never lose marks on this again.
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Side-by-Side Comparison
| Aspect | Intensive Property | Extensive Property |
|---|---|---|
| Depends on amount? | No | Yes |
| Examples | Density, boiling point, temperature, colour | Mass, volume, total enthalpy, heat capacity |
| Changes when sample is halved? | No | Yes |
| Use in calculations | Used to compare substances | Converted to intensive by dividing by mass or moles |
| Also called | Bulk properties | Size-dependent properties |
Memory Device
Intensive is independent of amount. Extensive extends with the amount.