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NCERT Class 11 Physics Chapter 11 Notes Thermal Properties of Matter - Download PDF

NCERT Class 11 Physics Chapter 11 Notes Thermal Properties of Matter - Download PDF

Edited By Vishal kumar | Updated on Jul 03, 2025 09:34 AM IST

Have you ever wondered how a thermometer determines your body temperature, why ice melts, or why metals feel colder than wood? Class 11 Physics Chapter 11: Thermal Properties of Matter provides a beautiful explanation of all these everyday phenomena. This chapter explains the effects of heat on solids, liquids, and gases as well as how variations in temperature lead to physical changes in matter. these NCERT notes for Class 11 Physics is prepared by subject matter expert in accordance with the most recent CBSE syllabus, and they are excellent for tests like the CBSE, JEE, and NEET.

In these NCERT notes for class 11 physics, you will explore important topics like heat transfer (conduction, convection, and radiation), specific and latent heat, Newton’s law of cooling, and thermal expansion etc. You will also find important formulas, simple explanations and relatable examples to make learning easier. Whether you are revising for boards or competitive exams, these NCERT notes for class 11 are very helpful for quick and effective understanding.

NCERT Class 11 Physics Chapter 11 Notes Thermal Properties of Matter - Download PDF
NCERT Class 11 Physics Chapter 11 Notes Thermal Properties of Matter - Download PDF

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NCERT Class 11 Physics Chapter 10 Notes

Temperature and Heat

Temperature is the measurement of a body's degree of hotness or coolness.
Example:-A cup of hot soup or an ice cream scoop

Heat is a kind of energy that is exchanged via temperature difference between two (or more) systems or between a system and its surroundings.
For example, a cup of hot coffee might be regarded an object or system, whereas everything else is the environment.

As a result of the temperature difference, heat will move from one thing to another.

The SI unit of Heat is joule.

Measurement of Temperature

A thermometer is used to determine the temperature.
In, liquid-in-glass thermometers, mercury and alcohol are regularly used liquids.
The following graph depicts the relationship between temperature in Celsius and Fahrenheit graphically:-

(tf32)/180=tc/100

Where tf means Fahrenheit temperature

tc means Celsius temperature

Absolute Temperature and the Ideal Gas Equation

A thermometer that employs any gas, on the other hand, will produce the same readings regardless of the gas used since all gases expand at the same rate at low temperatures.

The following variables are used to characterise the behaviour of gas:

  • Quantity(mass)

  • Pressure

  • Volume

  • Temperature

Gases with a low density obey the following rules: -

1. Boyle’s Law– In this law, the product of PV = constant(when temperature T is constant)

2. Charles’ Law- In this law, the ratio of V/T = constant (when pressure P is constant)

When both of the preceding principles are combined, the equation becomes PV = RT, where R stands for universal gas constant.

Absolute Zero


The minimal absolute temperature of an ideal gas is defined as Absolute Zero.
We get a straight line if we plot pressure versus temperature and then extend the line backwards to the x-axis, as seen in the graph below.

The lowest temperature measured (experimentally) was -273.15 °C, which is known as absolute zero.

The relationship between temperature in Kelvin and temperature in Celsius is provided by

T=tc+273.15

Thermal Expansion

Thermal expansion is the phenomenon of a body's dimensions expanding as its temperature rises.

Thermal Expansion Types

Expansion in length is known as linear expansion.

Expansion in the area is known as area expansion.

Volume Expansion: This is a term that refers to the increase in volume of anything.

Linear Expansion

The term "linear expansion" refers to the length of anything expanding as the temperature rises.

The term "linear expansion" refers to a fractional change in length or how the length changes in relation to the original length.

ΔL/L=αLΔT

ΔL is the length change, L is the initial length, ΔT is the temperature change, and αL is the linear coefficient of thermal expansion.

Area Expansion

The term "area expansion" refers to the expansion of an area as a result of an increase in temperature.

There is an increase in both length and width when an area is expanded.

ΔA/A=αaΔT

Where αa = coefficient of area expansion.

Volume Expansion

It is defined as the expansion of volume as a result of an increase in temperature.

This indicates that a substance's length, width, and height have increased.

ΔV/V=αvΔT

Where αv = coefficient of volume expansion.

Anomalous Behavior of Water

At 4 °C, water has the highest density.

When the temperature drops below 4 °C, the water expands, and the density falls.

Because of this feature, water in lakes and ponds only freezes at the top layer and not at the bottom, but if the water freezes at the bottom as well, animal and plant life would be unable to survive.


Specific heat capacity:

Heat Capacity

A quantity termed the heat capacity of a substance characterises the change in temperature of a substance when a particular amount of heat is absorbed or rejected by that substance.

S=ΔQ/ΔT

Where ΔQ is the amount of heat supplied to the substance and ΔT change in its temperature.

Specific heat is the amount of heat received or rejected per unit mass by a substance to change its temperature by one degree.

s=S/m

Molar specific heat capacity: -

The heat capacity per mole is the amount of heat (in moles) absorbed or rejected by a substance to change its temperature by one unit.

C=S/μ=ΔQ/μΔT

The molar specific heat capacity (Cp) is defined as follows:

The equivalent molar specific heat capacity at constant pressure is called molar specific heat capacity at constant pressure if the gas is retained at constant pressure during the heat transfer (Cp).

Molar specific heat capacity (Cv):-

The equivalent molar specific heat capacity at constant volume is called molar specific heat capacity at constant volume if the volume of the gas is maintained during the heat transfer (Cv).

Calorimetry

The word calorimetry comes from two parts:

  • Calorie, which means "heat"

  • Metry which means "measuring"

So, calorimetry is the process of measuring heat.

It involves the transfer of heat from a hotter body to a cooler body, while making sure that no heat is lost to the surroundings.

The basic idea behind calorimetry is that the heat lost by one body is equal to the heat gained by another. The device used to measure this heat transfer is called a calorimeter.

Change of State

A change of state is when a substance transitions from one form (solid, liquid, or gas) to another. For example:

  • Melting is when a solid (like ice) turns into a liquid (like water).

  • Fusion is the process where a liquid (like water) turns into a solid (like ice).

Thermal Equilibrium

In thermal equilibrium, there’s no heat gain or loss. The melting point of a substance is the temperature at which its solid and liquid states are in balance (equilibrium).

  • Normal Melting Point: This is the temperature at which a substance melts under standard atmospheric pressure.

Regelation

Regelation is the process where pressure lowers the freezing point of water, allowing ice to melt under pressure and refreeze when the pressure is reduced.

Vaporization

Vaporization is the process in which a liquid changes into a gas (for example, water turning into steam).

Sublimation

Sublimation is when a solid directly turns into a gas without becoming a liquid first. During sublimation, both the solid and gas forms exist in thermal equilibrium.


Latent Heat


Latent heat is the amount of heat energy required to change the state of a substance without changing its temperature. For example, during melting or boiling, a substance absorbs or releases heat but its temperature stays constant. There are two main types: latent heat of fusion (solid to liquid) and latent heat of vaporization (liquid to gas). This concept helps explain why ice melts or water boils at specific temperatures.

Heat Transfer

Heat transfer refers to the process by which thermal energy moves from a body at a higher temperature to one at a lower temperature. This transfer can occur in three primary ways:

Conduction – Transfer of heat through direct contact, mainly in solids. For example, a metal rod getting hot when one end is placed in a flame.

Convection – Transfer of heat through the movement of fluids (liquids or gases). Warm fluids rise and cooler fluids sink, creating a convection current. For instance, boiling water in a pot.

Radiation – Transfer of heat without a medium, in the form of electromagnetic waves. This is how the Sun heats the Earth.

Newton's Law of Cooling


Newton's Law of Cooling states that the rate at which a hot object cools down is directly proportional to the difference in temperature between the object and its surroundings, provided this difference is small. In simple words, the hotter the object compared to its surroundings, the faster it loses heat.


dTdt=k(TTsurrounding )


Where:

  • dTdt is the rate of change of temperature,
  • T is the temperature of the object,
  • Tsurrounding  is the surrounding temperature,
  • k is a constant depending on the nature of the object and the surrounding.


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Frequently Asked Questions (FAQs)

1. What do you mean by Vaporization as per Class 11 Thermal Properties of Matter notes?

Vaporization :-Vaporization is the process of changing from a liquid to a gas. 

The transition from a liquid to a vapour (or gas) is known as vaporisation.

2. What do you understand by Temperature?

Temperature is the measurement of a body's degree of hotness or coolness.
Example:- 

A cup of hot soup or an ice cream scoop 

3. What is Thermal Equilibrium?

Thermal Equilibrium: During this state, there is no heat loss or gain. 

4. What do you mean by Sublimation?

 Sublimation:-Sublimation is the transformation of a solid into a gas. 

Both the solid and vapour states of a substance coexist in thermal equilibrium throughout the sublimation (solid converts to vapour without going through liquid state) process. 

5. Is the 11 grade physics chapter 11 notes covering all of the important derivations?

No, the NCERT notes for Class 11 Physics chapter 10 do not include all of the important derivations. This NCERT note summarises the chapter's important points and equations and can be used to review the chapter's Thermal Properties of Matter.

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A block of mass 0.50 kg is moving with a speed of 2.00 ms-1 on a smooth surface. It strikes another mass of 1.00 kg and then they move together as a single body. The energy loss during the collision is

Option 1)

0.34\; J

Option 2)

0.16\; J

Option 3)

1.00\; J

Option 4)

0.67\; J

A person trying to lose weight by burning fat lifts a mass of 10 kg upto a height of 1 m 1000 times.  Assume that the potential energy lost each time he lowers the mass is dissipated.  How much fat will he use up considering the work done only when the weight is lifted up ?  Fat supplies 3.8×107 J of energy per kg which is converted to mechanical energy with a 20% efficiency rate.  Take g = 9.8 ms−2 :

Option 1)

2.45×10−3 kg

Option 2)

 6.45×10−3 kg

Option 3)

 9.89×10−3 kg

Option 4)

12.89×10−3 kg

 

An athlete in the olympic games covers a distance of 100 m in 10 s. His kinetic energy can be estimated to be in the range

Option 1)

2,000 \; J - 5,000\; J

Option 2)

200 \, \, J - 500 \, \, J

Option 3)

2\times 10^{5}J-3\times 10^{5}J

Option 4)

20,000 \, \, J - 50,000 \, \, J

A particle is projected at 600   to the horizontal with a kinetic energy K. The kinetic energy at the highest point

Option 1)

K/2\,

Option 2)

\; K\;

Option 3)

zero\;

Option 4)

K/4

In the reaction,

2Al_{(s)}+6HCL_{(aq)}\rightarrow 2Al^{3+}\, _{(aq)}+6Cl^{-}\, _{(aq)}+3H_{2(g)}

Option 1)

11.2\, L\, H_{2(g)}  at STP  is produced for every mole HCL_{(aq)}  consumed

Option 2)

6L\, HCl_{(aq)}  is consumed for ever 3L\, H_{2(g)}      produced

Option 3)

33.6 L\, H_{2(g)} is produced regardless of temperature and pressure for every mole Al that reacts

Option 4)

67.2\, L\, H_{2(g)} at STP is produced for every mole Al that reacts .

How many moles of magnesium phosphate, Mg_{3}(PO_{4})_{2} will contain 0.25 mole of oxygen atoms?

Option 1)

0.02

Option 2)

3.125 × 10-2

Option 3)

1.25 × 10-2

Option 4)

2.5 × 10-2

If we consider that 1/6, in place of 1/12, mass of carbon atom is taken to be the relative atomic mass unit, the mass of one mole of a substance will

Option 1)

decrease twice

Option 2)

increase two fold

Option 3)

remain unchanged

Option 4)

be a function of the molecular mass of the substance.

With increase of temperature, which of these changes?

Option 1)

Molality

Option 2)

Weight fraction of solute

Option 3)

Fraction of solute present in water

Option 4)

Mole fraction.

Number of atoms in 558.5 gram Fe (at. wt.of Fe = 55.85 g mol-1) is

Option 1)

twice that in 60 g carbon

Option 2)

6.023 × 1022

Option 3)

half that in 8 g He

Option 4)

558.5 × 6.023 × 1023

A pulley of radius 2 m is rotated about its axis by a force F = (20t - 5t2) newton (where t is measured in seconds) applied tangentially. If the moment of inertia of the pulley about its axis of rotation is 10 kg m2 , the number of rotations made by the pulley before its direction of motion if reversed, is

Option 1)

less than 3

Option 2)

more than 3 but less than 6

Option 3)

more than 6 but less than 9

Option 4)

more than 9

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