The Class 11 Chemistry Chapter 5 – States of Matter discusses the concepts including gaseous state, thermal energy, different laws, and various types of intermolecular force. To help students get a better understanding of the topics, the NCERT textbook has related questions at the end of Chapter 5.
Students can refer to NCERT Solutions for Class 11 Chemistry Chapter 5 – States of Matter to get accurate answers to the textbook questions. Subject-matter experts at Extramarks have prepared these solutions ensuring that they are easy to comprehend and have authentic answers to all the questions.
NCERT Solutions for Class 11 Chemistry Chapter 5 – States of Matter
Access NCERT Solutions for Class 11 Chemistry Chapter 5 – States of matter
Let us quickly give a glance at the Properties of the Four States of Matter
Solids: In solids, particles can vibrate at their own position, but they are not free to move as the molecules, atoms, and ions are all packed together closely. The application of an external force on solids can change their volume and shape.
Liquid: In liquids, the molecules, atoms, and ions are incompressible. When the pressure and temperature are constant, liquids have a fixed volume. Solids being exposed to high temperatures can become liquids, depending upon the properties of pressure.
Gas: In gases, the interacting particles have an intermolecular force of attraction with enough kinetic energy which changes the molecular forces to zero. The molecular space between the molecules in gases is large and hence liquids can be transformed into gaseous states.
Plasma: In this state of matter the ions are highly electrically conductive. The behaviour of matter is dominated by them due to the magnetic fields and currents they produce.
Factors like pressure, temperature, mass, and volume impact the behaviour of matter in different states of matter. Chemical reactions depend on the physical state of the matter, however, the chemical properties of a substance remain the same despite the change in state.
Intermolecular Forces
Intermolecular forces are forces that interact between the particles of matter, however, these are not to be confused with electrostatic forces. The force that exists between two oppositely charged ions is called electrostatic force. The types of Intermolecular forces in existence are:
- Dispersion Forces or London Forces
- Dipole-Dipole Forces
- Dipole-Induced Dipole Forces
- Hydrogen Bond
Thermal Energy
Thermal energy is the energy that arises when there is a motion of atoms and molecules in a body. It is the quantity of the particles’ average kinetic energy. The thermal energy increases with the increase in temperature.
Intermolecular Forces Vs Thermal Interactions
The thermal energy of particles keeps the molecules apart while the intermolecular forces of a substance keep them together. Hence, a balance between thermal energy and intermolecular forces of molecules results in the three states of matter.
Gaseous State
The physical properties of the molecules in the gaseous state are:
- Pressure is exerted by gases in all directions.
- Gases have a lower density as compared to solids and liquids.
- Gas molecules are highly compressible.
- Gases are completely miscible,i.e. they mix completely in all proportions.
- Gases do not have volume or a definite shape and can take the shape of the container.
- Gases have negligible intermolecular forces of attraction. Some experiments conducted led to the discovery of certain laws that regulate the behaviour of the molecules of gases.
Boyle’s Law
Under Boyle’s law, the pressure of the molecules of gas and its volume are inversely proportional under isothermal conditions.
P1V1=P2V2 (Under constant T)
Here V= Volume, T= Temperature, and P= Pressure.
If there is an expansion in a fixed amount of gas occupying volume V1 at pressure P1 under constant temperature T, it leads volume to become V2 and pressure to P2.
Charles’s Law
The direct relation between volume and absolute temperature under isobaric conditions is covered in Charles’ Law. This law discusses how gases expand with a rise in temperature and decrease in volume with a decrease in temperature.
V1=T2
V2= T1
Where V= Volume, P= Pressure, and T= Temperature
Gay-Lussac’s Law
Gay Lussac’s Law says that pressure exerted by a fixed amount of gas changes with the change in the absolute temperature of gas.
P ∝ T (at constant V)
Here, P= Pressure, V= Volume and T= Temperature
Avogadro Law
This law says that equal volumes of all gases contain equal numbers of molecules if they are under the same circumstances of pressure and temperature.
V ∝ n (at constant P and T)
Here n = number of molecules, V = Volume, P = Pressure, and T = Temperature.
Ideal Gas Equation
The ideal gas equation is an equation that was formed after combining all the three gas laws – Gay Lussac’s Law, Boyle’s Law, and Avogadro Law.
pV = nRT
Here V = Volume, p = Pressure, R = gas constant, n = number of molecules, and T = Temperature.
Dalton’s Law of Partial Pressure
Dalton’s Law of Partial Pressure says that the sum of partial pressures exerted by a mixture of non-reacting gases is equal to the total pressure exerted by them.
It should be noted here that in a mixture of gases, partial pressure is the pressure exerted by the individual gas.
Ptotal = p1 + p2 + p3 + ……..
Here, p1, p2, ……. are partial pressures.
Kinetic Theory of Gases
- A large number of identical molecules are found in gases.
- At ordinary temperature, molecules of gas do not have any force of attraction between them which is why gases expand and take up space.
- The actual volume occupied by molecules of gases is negligible because the distance between the molecules in gases is pretty large.
- The particles of gas travel in all directions in a straight line and collide against each other during their random motion.
- There is no loss of kinetic energy as the collision of the particles of gas is elastic in nature.
- Every molecule in the gases has a different speed which keeps on changing and so the energy of these molecules also keeps on changing.
Related Questions
Q1. What does matter mean?
A1. Everything that has mass and occupies space is called Matter. A Matter contains minute particles and can exist in multiple states like solid, gas, and liquid. An example of matter can be a stone or fruit juice or a pen or a newspaper. All of these things have mass and occupy space. The behaviour of matter is impacted by several factors like temperature, volume, etc.
Q2. What are the different states of matter?
A2. Matter has four different states;
- Solids: This state of matter has compact particles (molecules, atoms, and ions) closely packed with each other.
- Liquids: In the liquid state of matter, ions, atoms, and molecules are immiscible.
- Gas: In this state, the molecules of gases have large intermolecular spaces between them. Gases also have no fixed volume or shape.
- Plasma: In the plasma state of matter, ions are highly electrically conductive.
Students can study further about this chapter by referring to NCERT Solutions Class 11 Chemistry Chapter 5 by Extramarks.
Q3. What are the factors that affect the states of matter?
A3. States of matter are affected by factors like volume, pressure, temperature, and mass. Pressure on an object can cause it to condense, temperature causes an ice cube to melt while mass and volume play their own roles in impacting matter.