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

In Chapter 10 of NCERT Class 11 Physics, we learn about the thermal properties of matter and how various substances react when heat is introduced. The chapter discusses how heat transfers and influences the temperature of different materials.

The chapter on Thermal Properties of Matter has some important topics like:

• Temperature and Heat
• Temperature measurement methods
• Ideal gas equation
• Absolute temperature and absolute zero
• Changes in state (such as melting and boiling)

These CBSE Class 11 notes are designed by experts to enable you to have a good grasp of these concepts. They condense the key points of the chapter so that it is simple to revise and comprehend, but they don't delve too far into the derivations.

The notes are provided in PDF format, so you can download them for easy access anytime, anywhere, and refer to them as a convenient reference for your studies.

Also, students can refer,

• NCERT Solutions for Class 11 Physics Chapter 11 Thermal Properties of Matter
• NCERT Exemplar for Class 11 Physics Solutions Chapter 11 Thermal Properties of Matter

NCERT Class 11 Physics Chapter 10 Notes

Heat and 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

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.

Temperature Measurement

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:-

$(t_{\mathrm{f}}-32)/180=t_{\mathrm{c}}/100$

Where t_f means Fahrenheit temperature

t_c 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

$\mathbf{T}={\mathbf{t}}_c+273.15$

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.

$\mathrm{\Delta }L/L={\alpha }_L\mathrm{\Delta }T$

ΔL is the length change, L is the initial length, ΔT is the temperature change, and α_L 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.

$\mathrm{\Delta }\mathbf{A}/\mathbf{A}={\alpha }_{\mathrm{a}}\mathrm{\Delta }\mathbf{T}$

Where α_a = 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.

$\mathrm{\Delta }V/V={\alpha }_v\mathrm{\Delta }T$

Where α_v = 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.

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.

Mathematically,

$S=\mathrm{\Delta }Q/\mathrm{\Delta }T$

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

Specific heat capacity:

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

$\mathbf{s}=\mathbf{S}/\mathbf{m}$

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.

$C=S/\mu =\mathrm{\Delta }Q/\mu \mathrm{\Delta }T$

The molar specific heat capacity (C_p) 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 (C_p).

Molar specific heat capacity (C_v):-

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.

Significance of NCERT Class 11 Physics Chapter 10 Notes

Revisiting Chapter Content

The Thermal Properties of Matter Class 11 notes are a great resource for reviewing the main ideas and concepts of the chapter. They provide a clear and organized summary, helping you reinforce and clarify what you’ve learned.

Comprehensive Exam Preparation

These notes cover all the important topics from the Class 11 CBSE Physics syllabus, making them perfect for preparing for your board exams. They also serve as a strong foundation for preparing for competitive exams like VITEEE, BITSAT, JEE Main, NEET, and more.

Offline Study Resource: The availability of these Thermal Properties of Matter notes class 11 in PDF format allows for easy offline study. This feature is especially useful when access to the internet is restricted or unavailable, ensuring uninterrupted study sessions regardless of connectivity issues.

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