Explain intensive properties with two examples

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Q. Explain intensive properties with two examples

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Concept understanding — Intensive and Extensive Properties

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

Important

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 $30^\circ\text{C}$ and $50^\circ\text{C}$ , the final temperature is not $80^\circ\text{C}$ — 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.

Watch out

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)

Try it on a tricky one: electrical resistance. If you double the length of a wire, resistance doubles. If you double the cross-sectional area, resistance halves. So resistance depends on shape, not just amount — it's not purely extensive. That's why it's not in the table above. The clean classification works best for homogeneous systems where "amount" means mass or moles.

One Last Intuition

Think of intensive properties as the quality of matter — how hot, how dense, how concentrated. Extensive properties are the quantity — how much, how heavy, how voluminous. You can change the quantity without changing the quality, but not the other way around.

Tip

In exam problems, if you're asked to identify which property is intensive, look for the one that is a ratio of two extensive properties (density, specific heat, molar volume) or a field-like quantity (temperature, pressure). These are almost always intensive.

Students search 'intensive and extensive properties examples', 'intensive vs extensive properties class 11 chemistry', and 'thermodynamics properties important questions' while revising this topic, grounded in the NCERT-aligned CBSE Class 11 Chemistry Thermodynamics syllabus. Correctly classifying a given property, especially tricky ratios like density, is a quick, recurring question type in board exams and JEE Main.

Step 1. An intensive property is one whose value does not depend on the mass or size of the system -- it describes the CHARACTER of the substance, not its quantity.

Step 2. Temperature is intensive: a cup of boiling water and a vat of boiling water are both at $100^\circ$ C, regardless of the very different amounts of water.

Step 3. Density is intensive for the same reason: a drop and a barrel of the same liquid have identical density, since both mass and volume scale together and their ratio stays fixed. (Other valid examples from the chapter: refractive index, surface tension, boiling/freezing point, molar volume, molarity, molality, specific heat capacity.)

✓Final answer

Intensive properties are independent of the amount of substance present; examples: temperature, density.

Same / Similar Concept — real previous-year questions on the same or a closely similar concept, not this exact question.

CBSE 2026Set ANNUAL1 markMCQ
$Q. Which of the following is not extensive properties?$
(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.

Intensive properties do NOT depend on the amount of substance — density $= \dfrac{\text{mass}}{\text{volume}}$ stays the same whether you have 1 g or 1 kg of the substance, because both mass and volume scale together and the ratio cancels out.

✓Final answer
$Density is not an extensive property — option (d).$
CBSE 2026Set sz1 markMCQ
$Q. Select the correct one: Which one of the following is an extensive property$
(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.

Enthalpy (H = U + PV) is a state function that scales with the size of the system (2 mol of a substance has twice the enthalpy of 1 mol under the same conditions), so it is extensive.

Concentration (amount per unit volume), density (mass per unit volume), and viscosity (an intrinsic flow-resistance property) are all defined as ratios, so they remain unchanged regardless of how much of the substance is taken — all three are intensive.

✓Final answer
$The correct option is (a) Enthalpy.$
CBSE 2026Set ANNUAL1 mark
$Q. Fill in the blank: Those properties which do not depend on the quantity or size of matter present are known as ______ properties.$
›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.

Intensive properties do NOT depend on the quantity or size of matter present, e.g., temperature, density, pressure, concentration, and refractive index — these remain the same no matter how much substance is present.

✓Final answer
$Such properties are known as intensive properties.$
CBSE 2026Set ANNUAL1 markMCQ
$Q. Which of the following is an extensive property ?$
(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, pressure, density. Hence enthalpy is extensive; the other three are intensive.

✓Final answer
$(A) Enthalpy.$
CBSE 2025Set hz1 markMCQ
$Q. Select the correct one: Which of the following is an intensive property?$
(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.

Intensive properties: independent of the amount of matter, e.g. temperature, pressure, density, molar volume, refractive index, viscosity — these remain the same value whether you have 1 g or 1 kg of the substance.

Among the given options: Volume, Mass, and Internal energy all increase if you take more of the substance (extensive). Temperature does not change with the amount of substance present — it is intensive.

✓Final answer
$The intensive property is (b) Temperature.$
CBSE 2024Set ANNUAL1 markMCQ
$Q. Which of the following is an intensive property?$
(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 tension (force per unit length at a liquid surface) remain the same value regardless of how much liquid is present.

✓Final answer
$(D) Surface tension.$
CBSE 2024Set sz1 markMCQ
$Q. Select the correct one: Which of the following is an intensive property?$
(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.

Checking each option: Heat capacity -- extensive (doubles if the amount of substance doubles). Mass -- extensive by definition. Density = mass/volume -- since both mass and volume scale together with the amount of substance, their ratio stays constant, so density is intensive. Volume -- extensive (doubles if the amount doubles).

✓Final answer
$The correct option is (c) Density -- it is a mass-to-volume ratio, independent of the quantity of substance taken.$
CBSE 2022Set ANNUAL1 markMCQ
$Q. The intensive property among the quantities below is:$
(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.

Volume: scales with the amount of substance — extensive.

Only density (mass/volume) remains unchanged when the amount of substance changes.

✓Final answer
$The answer is (c) mass/volume — it is an intensive property, independent of the amount of substance.$
CBSE 2017Set ANNUAL1 mark
$Q. Explain extensive properties by appropriate examples.$
›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.

For instance, if you take 1 mole of water at a given temperature and combine it with another 1 mole of water at the same temperature, the combined mass, volume, and internal energy are exactly double that of one mole -- confirming these are extensive properties. This is in contrast to intensive properties like temperature, pressure, density, and molar volume, which stay the same regardless of how much material is present.

✓Final answer
$Extensive properties depend on the amount of matter in the system, e.g., mass, volume, internal energy, enthalpy, and heat capacity -- doubling the quantity of matter doubles the value of the property.$

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Q.Explain intensive properties with two examples

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