NEET Study Notes for State of Matter:Everything that surrounds us is made up of matter. Anything that occupies space and has mass is called matter. The different characteristics of matter enable us to classify them into- solids, liquids and gases, liquids. The other state in which matter can be found is called Plasma, Bose-Einstein Condensate and neutron degenerate matter.

• External Factors also influence the state of matter. For eg- On an increase in temperature, a substance may change its state from solid to liquid, liquid to gas through the process of vaporisation or solid to gas through sublimation.
• NEET Chemistry Syllabus is divided into three parts- Organic, Inorganic and Physical Chemistry. State of matter is an important unit of Physical Chemistry with 2-3 questions expected from this unit. NEET Study Notes for State of Matter will help you in understanding the topics to prepare for NEET 2022.

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Important Topics in NEET States of Matter

NEET Study Notes on State of Matter

Solid

• The particles in solid are tightly packed.
• Due to the nature of particles in solids, it has a defined volume and shape.
• Due to the space between particles, solids can be considered incompressible.
• The movements in particles is vibratory.
• Solids have very high density.

Liquid

• In comparison to solids, the particles in a liquid are packed less tightly.
• Due to the nature of particles, liquids do not have a definite shape.
• Liquids have low density.
• Due to the space between particles, their movements is slow.

Gases

• The particles move freely in the gaseous state.
• Due to the nature of particles, the Gaseous state of matter do not have a defined shape and volume.
• The density is very low.
• The gaseous state of matter is highly compressible.
• The kinetic energy of the particles is higher in comparison to liquids and gases.

Check NEET 2022 Syllabus

Intermolecular Forces and Types of Bonding

Attractive and repulsive forces that exist between the particles of a substance are called Intermolecular forces. Physical and chemical properties id substances are determined by the intermolecular forces between them. , For eg- if the intermolecular force between molecules is higher, the boiling point will also be high.

Intermolecular forces are also known as electrostatic forces. The intermolecular interactions are:

• Ion- Dipole Interaction- Ion-Dipole interactions occur between ions and polar molecules. This intermolecular interaction is affected by polar molecule size, ion size and charge and dipole moment magnitude.

Example- On combining NaCl with water, Ion dipole interaction occurs between polar water molecules and sodium chloride ions.

• Dipole-Dipole Interaction-

The attractive forces between polar molecules is called the Dipole-Dipole interaction. The difference in electronegativity due to the covalent bond gives rise to Polar molecules with permanent dipoles. The positive part of a molecule is attracted to the negative part of the other molecule.

Example- In HCL molecules, dipole-dipole interactions occur, The electronegative element of Chlorine is more than Hydrogen. Hydrogen attracts a positive charge whereas Chlorine attracts a negative charge.

• Ion Induced Dipole Interaction-

An ion is placed near a non-polar molecule for polarization. Due to this the non-polar molecules become charged and acts as induced dipoles. This bond between ions and induced dipoles is called the Ion induced dipolar interaction.

• Dipole Induced Dipole interaction

When polar molecules are placed near non-polar molecules, the transformation of non-polar molecules into induced dipoles. This interaction is known as dipole-induced dipole interaction. On damage of the electron cloud, the molecule acts as a dipole polar molecule permanent dipole transforms the neutral molecule's dipole.

• Dispersion Forces- Dispersion Forces are also called London forces. This interaction occurs due to the electron movement that creates positive and negative regions. The non-polar molecules and atoms that are electronically charged are disturbed in symmetry. This is why they exist in dipole moments. Dispersion Forces are the weakest force and travel across a short distance.

Read:

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What are Gas Laws?

Laws that describe the relationship among thermodynamic temperature (T), pressure and volume of a gas are known as Gas Laws.

Boyle’s Law

In a given mass of gas, the volume is inversely proportional to the pressure at constant temperature

V ∝ 1 / p or PV = K

where K is constant and its value depends on mass, temperature, and nature of gas

On mass and temperature being equal 

As Density is inversely proportional to 1/V

Hence P ∝ D

Charles Law

At constant pressure, volume of given mass of gas is directly proportional to the temperature

V ∝ T

where V is the volume of gas

T is the temperature

Gay-Lussac Law

At constant volume, the pressure of the specified mass of gas is directly proportional to the temperature.

V ∝ T or

Avogadro’s Law

At constant temperature and pressure, the volume of gas is directly proportional to to the number of molecules. Thus if the volume of gas is the equal number of moles or molecules will also be equal to the ideal gas only when the volume is equal.

Mathematically, Avogadro’s Law can be expressed as

V/n is constant

or

where v is the volume of gas

n is the number of molecules

Combined Gas Law

This law is also known as general gas equation. When Charle’s law, Boyle’s Law and Gay-Lussacs’s law is combined, combined gas law is obtained. The relationship between volume, pressure and temperature for a specific volume of gas is determined.

Mathematically, combined gas law is expressed as

PV/T = k

What is Ideal Gas?

Ideal gas is also known as perfect gas as the relationship among pressure, volume, temperature and gas quantity is established.

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Ideal Gas Law

Ideal Gas Law is established by a combination of the four laws- Gay Lussac Law, Avogadro’s Law, Charles, and Combined Law. In this law, combined gas law is transformed into ideal gas law and the addition of Avogadro’s law takes place.

Ideal Gas Law can be represented as

PV = nRT

Where for the gas,

P is the pressure

R is the universal gas constant

V is the volume

n is the number of molecules

T is temperature

Kinetic Theory of Gases

• Particles- Gaseous state of matter is composed of particles known as molecules.
• The mass occupied by gas molecules is negligible.
• The movement of particles is random and this leads to the collision of molecules.
• Due to the perfectly elastic nature of molecules, loss of kinetic energy due to collisions does not happen.
• Due to the collision of gas molecules against the container walls, the pressure of gas is exerted. This pressure of gas is directly proportional to the collisions in unit time per unit area on the container walls.
• Due to the motion of particles, the kinetic energy of particles is directly proportional to the temperature of the gas.

Kinetic Gas Equation

Mathematically Kinetic Gas Equation can be represented as

PV = 1/3mNU²

where m is the mass of molecule gas

N is the number of molecules

U = Root mean square velocity

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Van Der Waal’s Equation

For one mole of gas, Van Der Waal’s Equation is

where b is the co-volume

a is the attractive force magnitude between molecules of gas

• When the value of a is greater the strength of Van Der Waal’s force will also be greater. Due to this gas can be liquified easily.

Critical Temperature and Liquefaction of Gases

The increase and decrease of temperature causes the liquefication of gases,

Critical Temperature is the temperature above which gas cannot be liquified, even if the pressure is high. For example- The critical temperature of CO₂ is 31.1°C.

Liquefaction of Gases

Gas can be liquified by two main factors

• Pressure Increase- Pressure Increase increases molecule attraction.
• Temperature Decrease- Temperature decrease, decreases the molecular kinetic energy. This temperature of gas will be lower than the critical temperature.
• Liquefaction of Gas is also based on other principles like cooling by freezing mixture, Claude’s method, and Linde’s Method.

Liquid State

The state of Liquid is composed of molecules that are small and due to the weak intermolecular force, molecules of the liquid are in constant motions that are random. The kinetic energy of liquid molecules is directly proportional to the temperature.

• In increasing order of strength, the intermolecular forces are

Induced dipole<dipolle attraction<Hydrogen bonding

• In liquids, due to the gap between molecules, there is no definite shape, the liquid molecules occupy the shape of the container.
• The diffusion rate is slower in comparison to gases, the compressibility of liquids is also less.
• When liquid is converted into vapor at room temperature, it is the process of evaporation.

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Vapour Pressure

The pressure exerted by the vapor phase or condensed phase in a state of equilibrium at a specific temperature is called vapor pressure or vapor equilibrium pressure. Vapor pressure depends upon the following factors:

• Intermolecular interaction- if the intermolecular interaction between liquids is weak, then the vapor pressure of such liquid tends to be high.
• Temperature- with an increase in temperature, the vapor pressure of liquid increases.

Surface Tension

Surface tension is defined as the force that acts on the liquid surface and has a tendency to shrink the surface area. S.I unit of Surface tension is Nm^–1. Drop Number method can be used for measuring surface tension.

Surface tension depends upon

• Intermolecular attraction- when intermolecular attraction is strong, surface tension also increases.
• Temperature- With an increase in temperature, surface tension tends to decrease.

Viscosity

The friction force that acts between layers of liquid that are in movement across each other with different velocities is called viscosity. In order to compare the viscosity of liquids, coefficient of viscosity is used. S.I unit of Viscosity is Nsm²

• Intermolecular Interaction- When the intermolecular attraction between liquids is strong, viscosity also increases.
• Temperature- temperature and viscosity are inversely proportional to each other.

Read NEET Study Notes on Chemical Kinetics

Boiling Point

The temperature at which the vapor pressure is equal to the atmospheric pressure of the liquid is called the Boiling Point.

NEET Sample MCQs on State of Matter

Question: According to which law, at constant pressure, the volume of an ideal gas is directly proportional to its temperature?

1. Joule’s Law
2. Avogadro’s Law
3. Boyle’s Law
4. Charle’s Law

Answer: Charle’s Law

Question: In which property of gases, is a constant R or universal gas constant observed?

1. Halogen gases
2. Inert gases
3. Ideal gases
4. All of the above

Answer: Ideal gases

Question: Which condition is necessary for Charle’s Law?

1. Constant temperature
2. Constant volume and pressure
3. Constant pressure
4. Constant volume

Answer: constant pressure

Question: What is the necessary condition for carbon monoxide to operate on the ideal gas law?

1. High temperature, low pressure
2. Low temperature, high pressure
3. High temperature, high pressure
4. Low temperature, low-pressure

Answer: high temperature, low-pressure

Question: How much will gas molecule’s average velocity increase when the temperature is doubled?

1. 2.8
2. 2
3. 1.4
4. 4

Answer: 1.4

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