Q.Define the following terms:
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Intensive and Extensive Properties
Imagine you have a cup of hot tea. You take a sip — it's hot. Now pour half of it into another cup. Is the tea in each cup still hot? Yes, it is. The temperature didn't change just because you split the tea. Now think about the volume: each cup now has less tea than the original. The volume did change.
That's the entire intuition in one sip.
Temperature is an intensive property — it doesn't care how much tea you have. Volume is an extensive property — it cares a lot.
The Precise Definition
An intensive property is independent of the amount of matter present. An extensive property depends on the amount of matter.
If you take a system and cut it into two equal halves, any property that stays the same in each half is intensive. Any property that gets halved is extensive.
| Intensive (stays same) | Extensive (gets halved) |
|---|---|
| Temperature | Mass |
| Pressure | Volume |
| Density | Energy |
| Concentration | Number of moles |
| Refractive index | Heat capacity |
| Viscosity | Entropy |
Notice something: density is mass divided by volume. Both mass and volume are extensive, but their ratio is intensive. That's a powerful pattern — ratios of extensive properties are always intensive.
Why This Matters
In thermodynamics, you cannot simply add intensive properties. If you mix two buckets of water at 30∘C and 50∘C, the final temperature is not 80∘C — it's somewhere in between. But you can add extensive properties: the total mass is the sum of the two masses, the total volume is the sum of the two volumes.
A common mistake: thinking that "intensive" means "always constant." Temperature is intensive but it can change — it just doesn't change because you change the amount.
The Decisive Test
Here's a foolproof way to classify any property. Ask yourself:
If I double the amount of substance, does this property double?
- Yes → Extensive (mass, volume, energy, charge)
- No → Intensive (temperature, pressure, density, colour) …
These are three standard thermodynamics definitions, distinguishing how a property scales with the amount of matter present, how a system's boundary permits exchange with its surroundings, and the reference conditions used for a reaction's enthalpy change. …
Three standard thermodynamic definitions: extensive property (mass-dependent), closed system (energy but no matter exchange), and standard enthalpy of reaction (ΔH under standard-state conditions).
- Extensive properties: Properties whose value depends on the quantity or size of matter present in the system. Examples: mass, volume, internal energy, enthalpy, heat capacity. (Contrast with intensive properties like temperature, pressure, density, which do not depend on amount.)
- Closed system: A system that can exchange energy (heat and work) with its surroundings but cannot exchange matter with it. The boundary is permeable to energy but not to mass. Example: a sealed, non-insulated container of gas — it can be heated/cooled and can do work, but no gas escapes or enters. …
- CBSE 2026Set ANNUAL1 markMCQQ.Which of the following is not extensive properties?(a) Mass(b) Volume(c) Enthalpy(d) Density
›Reveal solutionSolution
Density is an intensive property because it is a ratio (mass/volume) that doesn't change with the amount of substance.
Extensive properties depend on the quantity of matter present in the system — mass, volume, and enthalpy all double if you double the amount of substance.
…
- CBSE 2026Set sz1 markMCQQ.Select the correct one: Which one of the following is an extensive property(a) Enthalpy(b) Concentration(c) Density(d) Viscosity
›Reveal solutionSolution
Enthalpy depends on the amount of substance present, so it is extensive; concentration, density, and viscosity are all ratios that stay constant regardless of sample size, so they are intensive.
Thermodynamic properties are classified as:
- Extensive properties: depend on the quantity/mass of matter present in the system (e.g. mass, volume, internal energy, enthalpy, entropy, heat capacity). If you double the amount of substance, an extensive property doubles too.
- Intensive properties: do NOT depend on the quantity of matter present (e.g. temperature, pressure, density, concentration, viscosity, refractive index, molar properties). These stay the same whether you have 1 g or 1 kg of the substance. …
- CBSE 2026Set ANNUAL1 markQ.Fill in the blank: Those properties which do not depend on the quantity or size of matter present are known as ______ properties.
›Reveal solutionSolution
Properties independent of the amount of matter are called intensive properties; those that depend on the amount are called extensive properties.
Matter's physical properties are classified into two types based on how they behave when the amount of substance changes:
- Extensive properties depend on the quantity or size of matter present, e.g., mass, volume, and total energy — doubling the amount of substance doubles these. …
- CBSE 2026Set ANNUAL1 markMCQQ.Which of the following is an extensive property ?(a) Enthalpy(b) Temperature(c) Pressure(d) Density
›Reveal solutionSolution
Enthalpy is the extensive property here.
Extensive properties depend on the amount of substance (they add up), e.g. mass, volume, enthalpy, internal energy. Intensive properties are independent of amount, e.g. temperature, pres …
- CBSE 2025Set hz1 markMCQQ.Select the correct one: Which of the following is an intensive property?(a) Volume(b) Temperature(c) Mass(d) Internal energy
›Reveal solutionSolution
Intensive properties are independent of the quantity of matter; temperature is intensive, while volume, mass and internal energy are all extensive (they scale with amount of substance).
Thermodynamic properties are classified as:
- Extensive properties: depend on the amount (mass or moles) of matter in the system, e.g. volume, mass, internal energy, enthalpy, entropy, heat capacity — if you double the amount of substance, these double too. …
- CBSE 2024Set ANNUAL1 markMCQQ.Which of the following is an intensive property?(a) Volume(b) Mass(c) Enthalpy(d) Surface tension
›Reveal solutionSolution
Surface tension is intensive; volume, mass, and enthalpy are extensive.
Extensive properties depend on the amount of matter present (they add up when systems combine) — mass, volume, and enthalpy are all extensive. Intensive properties are independent of the quantity of matter — e.g. temperature, density, pressure, and surface ten …
- CBSE 2024Set sz1 markMCQQ.Select the correct one: Which of the following is an intensive property?(a) Heat capacity(b) Mass(c) Density(d) Volume
›Reveal solutionSolution
Density is an intensive property because it is a ratio (mass/volume) that does not change with the quantity of matter, unlike heat capacity, mass, or volume, all of which are extensive.
Extensive properties depend on the amount (mass or size) of the system -- examples include mass, volume, and heat capacity (the total heat capacity of 2 kg of a substance is twice that of 1 kg). Intensive properties do not depend on the amount of matter -- examples include density, temperature, pressure, molar heat capacity, and refractive index.
…
- CBSE 2022Set ANNUAL1 markMCQQ.The intensive property among the quantities below is:(a) enthalpy(b) mass(c) mass/volume(d) volume
›Reveal solutionSolution
Intensive properties (density, temperature, pressure, molar quantities) stay the same regardless of the amount of substance; extensive properties (mass, volume, enthalpy) scale with the amount.
Check each option:
- Enthalpy: depends on the amount of substance present (double the mass, double the enthalpy) — extensive.
- Mass: obviously scales with amount of substance — extensive.
- Mass/volume (density): if you take twice the amount of a substance, both mass and volume double, so their ratio (density) stays the same — intensive. …
- CBSE 2017Set ANNUAL1 markQ.Explain extensive properties by appropriate examples.
›Reveal solutionSolution
Extensive properties scale with the size/quantity of the system (e.g., mass, volume, internal energy); this is unlike intensive properties, which are independent of the amount of matter present (e.g., temperature, pressure, density).
A thermodynamic property is called extensive if its value for the whole system is obtained by adding up its values for the individual parts of the system -- in other words, it depends on the size or amount of matter present.
Examples of extensive properties:
- Mass: doubling the amount of a substance doubles its mass.
- Volume: 2 litres of water occupies twice the volume of 1 litre of water.
- Internal energy (U): the total energy content scales with the amount of substance.
- Enthalpy (H): similarly depends on the quantity of substance present.
- Heat capacity and the total number of moles (n): both scale with the size of the sample. …
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