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Changing States of Matter - Solid, Liquid And Gas

Changing States of Matter - Solid, Liquid And Gas

Vishal kumarUpdated on 02 Jul 2025, 05:04 PM IST

In this article we are going to learn about changing states of matter, Transformation between solid, liquid, gas and many more.
Can Matter Change Its Shape
The answer is definitely 'Yes.'
It has the ability to modify its shape, size, and volume.
You've probably noticed how ice cubes melt from solid to liquid water or how water boils into vapour, but have you ever wondered why objects change form?

Changing States of Matter - Solid, Liquid And Gas
Changing States of Matter

When matter loses or absorbs energy, its condition changes.

When a substance absorbs energy, its atoms and molecules travel faster, and the extra kinetic energy pushes particles far enough to change form.

Typically, this energy is heat or thermal energy.

Let us look at the science behind the changing states of matter in this article.

Define Changes of State?

Change in state of matter is the change in the physical properties.

These variations do not require any chemical changes.

Deposition sublimation condensation evaporation melting, freezing, and vaporisation are the examples of change in states.

Also read -

Why Do Phase Changes Happen?

When the temperature or pressure of a system varies, phase changes occur.

When the temperature or pressure rises, so does the interaction between the molecules.

Similarly, as the temperature drops, it becomes easier for molecules and atoms to form a more rigid structure.

Transitions Between Liquids and Solids

Freezing

Heat transmission happens between the warmer tray and the freezer's colder air.

The heat from the heated water is lost to the cold air in the freezer.

This heat transfer continues until there is no more energy available for the particles to move past each other.

This forces them to remain in fixed locations, held together by the force of attraction.

This method converts liquid water into solid ice.

The transformation of liquid to solid is called Freezing.

The freezing point is the temperature at which it happens.

Also read :

Melting

solid to liquid examples

If you pulled the ice cubes out of the freezer and placed them in a warm area, the ice would absorb energy from the warmer air.

This absorbed energy would help them overcome the force of attraction that was holding them together, allowing them to slip out of the frozen posture they were in.

The transformation of solid to liquid is called Melting.

Temperature at which both solid and liquid are in equilibrium is called the melting point of a solid.

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Liquid-to-Gas Transition/Water gas state transition

This process can be explained using the experiment:

Water gets heated up when the pot is filled with cold water and heated.

The heat energy is absorbed by the water.

Vaporization

This occurs when liquid water particles have enough energy to totally overcome the force of attraction between them and transition to the gaseous form.

The Transformation of liquid to vapor/liquid to gas is vaporization. This is also called boiling.

The boiling point of a liquid is the temperature at which it begins to boil.

Condensation

The process by which water vapor is transformed to liquid is called condensation.

When hot water comes in contact with cooler surfaces, it cools and loses energy and it evaporates and cooler water loses energy to overcome the attractive forces.

They combine to produce droplets of liquid water.

So, transformation of gas to liquid is called Condensation.

Transitions between Solids and Gases

When transformation from Solid to gas occurs then solid must first pass through the liquid stage.

However, solids can sometimes transition straight to gases without passing through the liquid state.

The opposite can also happen.

Gases can sometimes convert directly to solids.

NCERT Physics Notes :

Sublimation

It is a solid to gas process.

The Transformation of solid to gas is called sublimation.

When solids absorb enough energy to entirely overcome the forces of attraction between them, this happens.

Dry ice is an example of a solid that sublimates.

All these can be observed in the change of state experiments.

Conclusion
Every item in existence undergoes a state transition, which may be of interest to you.

It is simply a matter of how much heat is applied to the substance.

Everything on our planet can be manipulated to change its state if enough heat is applied.

The truth is, not every substance has to go through the solid-liquid-gas cycle.

Some compounds can naturally transition from a solid to a gaseous state without entering the liquid state.

Sublimation is the name given to this phenomenon.

Sublimation occurs in the elements iodine, dry ice (solid CO2), and high-quality coal, which burns and sublimates into vapour at high temperatures.

Also check-

Commonly Asked Questions

Q: Why does water expand when it freezes, unlike most other substances?
A:
Water expands when it freezes due to its unique molecular structure. As water cools, the molecules form a crystalline structure with hexagonal rings, creating more space between molecules. This unusual property is why ice floats on water and why frozen pipes can burst.
Q: How does pressure affect the melting and boiling points of substances?
A:
Increased pressure generally raises the melting and boiling points of substances. For melting, higher pressure makes it harder for particles to move apart. For boiling, increased pressure makes it more difficult for vapor bubbles to form and escape the liquid. However, there are exceptions, like water's melting point, which decreases slightly under pressure.
Q: Why do some solids sublimate instead of melting?
A:
Solids sublimate when the vapor pressure of the solid is greater than the atmospheric pressure at temperatures below the melting point. This occurs in substances with weak intermolecular forces, where particles can transition directly from the solid to gas state without passing through the liquid phase. Examples include dry ice (solid CO2) and iodine.
Q: What causes matter to change from one state to another?
A:
Matter changes state when energy is added or removed, typically in the form of heat. When enough energy is added, particles overcome intermolecular forces, causing solids to melt into liquids or liquids to vaporize into gases. Conversely, when energy is removed, particles slow down and come closer together, causing gases to condense into liquids or liquids to freeze into solids.
Q: What is the difference between evaporation and boiling?
A:
Evaporation occurs at the surface of a liquid at any temperature, while boiling occurs throughout the liquid at a specific temperature (the boiling point). Evaporation is a gradual process that happens when some particles gain enough energy to escape the liquid's surface. Boiling occurs when the vapor pressure of the liquid equals the atmospheric pressure, causing rapid vaporization throughout the liquid.

Frequently Asked Questions (FAQs)

Q: What is the significance of the glass transition in amorphous solids?
A:
The glass transition is a reversible change in amorphous materials from a hard, brittle state to a molten or rubber-like state. Unlike crystalline solids, glasses don't have a sharp melting point but gradually soften over a range of temperatures. Understanding the glass transition is crucial in materials science, affecting the properties and processing of plastics, glasses, and some pharmaceuticals.
Q: How do phase diagrams help us understand the behavior of substances under different conditions?
A:
Phase diagrams are graphical representations showing how temperature, pressure, and physical state relate for a substance. They help predict which state a substance will be in under specific conditions, where phase transitions occur, and how changes in temperature or pressure affect the state. Phase diagrams are essential tools in chemistry, physics, and engineering for understanding and manipulating material properties.
Q: How do nanomaterials exhibit different melting and boiling points compared to bulk materials?
A:
Nanomaterials often have lower melting and boiling points than their bulk counterparts due to the increased surface area-to-volume ratio. Surface atoms have fewer neighboring atoms and are less tightly bound, requiring less energy to overcome intermolecular forces. This phenomenon, known as the melting-point depression, becomes significant at the nanoscale and has implications for nanotechnology applications.
Q: Why do some substances, like dry ice, sublimate at atmospheric pressure?
A:
Substances like dry ice (solid CO2) sublimate at atmospheric pressure because their triple point (where solid, liquid, and gas phases coexist) occurs at a pressure higher than atmospheric pressure. At normal atmospheric conditions, these substances transition directly from solid to gas as they warm up, bypassing the liquid phase. This property makes dry ice useful for cooling without leaving a liquid residue.
Q: What is the role of nucleation in phase changes, particularly in crystallization and boiling?
A:
Nucleation is the initial process in a phase transition where small clusters of molecules form the new phase. In crystallization, it involves the formation of tiny crystal nuclei. In boiling, it's the formation of vapor bubbles. Nucleation can be homogeneous (spontaneous) or heterogeneous (assisted by impurities or surfaces). Understanding nucleation is crucial in controlling crystal growth, preventing supercooling, and designing materials with specific properties.
Q: How do pressure cookers utilize the relationship between pressure and boiling point?
A:
Pressure cookers increase the pressure inside the container, which raises the boiling point of water above 100°C (212°F). This higher boiling point allows food to cook at a higher temperature, reducing cooking time and often resulting in more tender food. The relationship between pressure and boiling point demonstrated in pressure cookers is an application of the Clausius-Clapeyron equation in thermodynamics.
Q: What is the difference between an amorphous solid and a crystalline solid in terms of phase transitions?
A:
Crystalline solids have a regular, repeating atomic structure and typically have sharp melting points. Amorphous solids, like glass, lack this ordered structure and gradually soften over a range of temperatures rather than having a distinct melting point. This difference affects how these materials behave during phase transitions and influences their physical properties and applications.
Q: How do phase changes in water affect climate and weather patterns?
A:
Water's phase changes play a crucial role in climate and weather. Evaporation from oceans absorbs heat, while condensation in clouds releases heat, driving atmospheric circulation. The formation and melting of ice affect ocean currents and global heat distribution. Understanding these processes is essential for climate modeling, weather prediction, and studying phenomena like the urban heat island effect.
Q: Why do some materials expand when they freeze while others contract?
A:
Most materials contract when freezing because particles in the solid state are more closely packed than in the liquid state. However, some materials, like water, expand when freezing due to their molecular structure. In water, hydrogen bonds create a hexagonal crystal structure with more space between molecules. Understanding these exceptions is crucial in geology, construction, and materials science.
Q: What is the role of pressure in determining the state of matter for a given substance?
A:
Pressure plays a crucial role in determining the state of matter by affecting the balance between intermolecular forces and particle kinetic energy. Increased pressure generally favors more condensed states (solid or liquid) by forcing particles closer together. This principle explains why deep-sea creatures can withstand extreme pressures and why pressure cookers work. It's also vital in understanding planetary atmospheres and geological processes.
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