Changing States of Matter - Solid, Liquid And Gas

Edited By Vishal kumar | Updated on Jul 02, 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

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.

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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-

Frequently Asked Questions (FAQs)

1. What do solids become when they reach their melting point?

When a solid reaches its melting point, it transforms into a liquid.

2. What is the temperature at which the water boils?

The temperature at which a pure liquid transforms into a gas is referred to as the boiling point.

3. What exactly is the melting point?

The melting point is the temperature at which a material begins to melt.

4. What is the process through which solids turn directly into gases?/Explain gas to solid process.

Sublimation is defined as the process by which a solid transitions to a gaseous state without becoming a liquid.

5. What exactly is evaporation?

Evaporation occurs when a liquid is transformed to a gas at any temperature.

6. Change in state definition?/What is meant by change of state?Mention different states of process.

A physical change in a matter is referred to as a change of condition.

They are reversible alterations that do not require any changes in the matter's chemical makeup.

Melting, freezing, evaporation, sublimation, condensation are examples of common state changes.

7. Write examples of change of state of matter in everyday life/Write change of state examples.

Change of water to ice, transform of liquid to crystal.

8. Write gas to liquid process name.

Condensation

9. What are evaporation condensation sublimation?

Evaporation: Evaporation occurs when a liquid is transformed to a gas at any temperature.

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

Sublimation: The Transformation of solid to gas is called sublimation.

10. What is vapour to solid or gas to liquid?

Change of state from gas to solid or vapor to solid is called deposition/deposition gas to solid.

It is an example of solidification from gas to solid.

11. Water in the form of a gas is called as ____

Water vapor

12. Why does water expand when it freezes, unlike most other substances?

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.

13. How does pressure affect the melting and boiling points of substances?

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.

14. Why do some solids sublimate instead of melting?

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.

15. What causes matter to change from one state to another?

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.

16. What is the difference between evaporation and boiling?

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.

17. Why do sweating and evaporative cooling work better in dry climates?

Sweating and evaporative cooling are more effective in dry climates because the rate of evaporation depends on the humidity of the surrounding air. In dry air, water molecules can more easily escape into the atmosphere, taking heat energy with them. In humid conditions, the air is already saturated with water vapor, slowing down evaporation and reducing cooling efficiency.

18. How does the kinetic theory of matter explain the behavior of particles in different states?

The kinetic theory of matter explains that particles in all states are in constant motion, but their behavior differs. In solids, particles vibrate in fixed positions. In liquids, particles can move around each other but remain close. In gases, particles move freely with large spaces between them. As temperature increases, particle motion increases, leading to state changes as intermolecular forces are overcome.

19. How does surface tension relate to the liquid state of matter?

Surface tension is a property of liquids caused by cohesive forces between molecules at the surface. These forces pull the surface molecules inward, creating a "skin-like" effect. Surface tension explains phenomena like water beading on surfaces, insects walking on water, and capillary action. It's strongest in liquids with strong intermolecular forces, like water.

20. What is supercritical fluid, and how does it relate to phase changes?

A supercritical fluid is a substance at a temperature and pressure above its critical point, where distinct liquid and gas phases no longer exist. It has properties of both gases (filling its container) and liquids (dissolving materials). Supercritical fluids are important in industrial processes and occur in nature, such as in the interiors of gas giants like Jupiter.

21. What is plasma, and how does it relate to the other states of matter?

Plasma is often called the fourth state of matter. It's an ionized gas where electrons have been stripped from atoms, creating a mixture of charged particles. Plasma forms at very high temperatures or under strong electromagnetic fields. Unlike the transition between other states, the change to plasma is more gradual and involves the breaking of atomic bonds rather than just intermolecular forces.

22. Why do some gases not liquefy at room temperature regardless of pressure?

Gases that don't liquefy at room temperature regardless of pressure are called supercritical fluids above their critical temperature. At this point, the kinetic energy of the particles is too high for intermolecular attractions to hold them in a liquid state, no matter the pressure. Examples include helium, which must be cooled below -268°C to liquefy at atmospheric pressure.

23. How does the process of deposition (gas to solid) differ from condensation and freezing?

Deposition is the direct transition of a substance from gas to solid without passing through the liquid phase. Unlike condensation (gas to liquid) or freezing (liquid to solid), deposition occurs when gas molecules lose enough energy to form a solid structure directly. This process is less common but occurs in nature, such as in the formation of frost or snowflakes from water vapor in the air.

24. What role does latent heat play in weather patterns and climate?

Latent heat plays a crucial role in weather and climate. When water evaporates from oceans, it absorbs heat, cooling the surface. This heat is released when the water vapor condenses in the atmosphere, warming the air and providing energy for storms. The large latent heat of water helps moderate Earth's climate and drives the water cycle, influencing precipitation patterns and atmospheric circulation.

25. How does the concept of critical point relate to phase transitions?

The critical point is the end point of the vapor-liquid coexistence curve on a phase diagram, where the properties of the liquid and gas phases become indistinguishable. Beyond this point, increasing temperature or pressure doesn't cause a phase change. Understanding the critical point is crucial in industrial processes, such as supercritical fluid extraction, and in studying the behavior of fluids under extreme conditions.

26. How does the presence of dissolved gases affect the boiling process of liquids?

Dissolved gases in liquids can significantly affect the boiling process. They provide nucleation sites for bubble formation, often leading to a lower apparent boiling point and more vigorous boiling. This is why degassed water can be superheated above its normal boiling point. Understanding this phenomenon is important in laboratory techniques, cooking, and industrial processes involving liquids and gases.

27. What is the significance of the Leidenfrost effect in phase changes?

The Leidenfrost effect occurs when a liquid comes into contact with a surface significantly hotter than its boiling point. A vapor layer forms between the liquid and the surface, insulating the liquid and causing it to hover. This effect explains why water droplets dance on a very hot pan and has implications for cooling systems, safety in handling cryogenic liquids, and some industrial processes involving high temperatures.

28. How does superconductivity relate to phase changes in matter?

Superconductivity is a quantum mechanical phenomenon where certain materials, when cooled below a critical temperature, exhibit zero electrical resistance and expel magnetic fields. While not a classical phase change, it can be considered a phase transition from a normal to a superconducting state. Understanding this transition is crucial in developing technologies like MRI machines and potential future applications in energy transmission.

29. How do quantum effects influence phase transitions at extremely low temperatures?

At extremely low temperatures, quantum effects become significant in phase transitions. Phenomena like Bose-Einstein condensation, where particles collapse into the same quantum state, represent a new kind of phase transition. Superfluidity in helium is another example where quantum effects lead to unusual fluid behavior. These quantum phase transitions are important in understanding fundamental physics and developing new technologies.

30. What is the role of latent heat in the formation of severe weather events like hurricanes?

Latent heat plays a crucial role in the formation and intensification of hurricanes. As warm

31. How does adding impurities affect the melting and boiling points of a substance?

Adding impurities generally lowers the melting point and raises the boiling point of a substance. Impurities disrupt the crystal structure of solids, making it easier to break apart (lowering the melting point). In liquids, impurities interfere with vapor formation, requiring more energy to overcome intermolecular forces (raising the boiling point). This principle is used in applications like de-icing roads with salt.

32. What is supercooling, and why does it occur?

Supercooling is the process of lowering a liquid's temperature below its freezing point without it becoming solid. It occurs when a liquid lacks nucleation sites (impurities or surface irregularities) for crystals to form. Supercooled liquids are in a metastable state and can rapidly freeze when disturbed or when a nucleation site is introduced.

33. How does the latent heat of fusion differ from the latent heat of vaporization?

Latent heat of fusion is the energy required to change a substance from solid to liquid at its melting point, while latent heat of vaporization is the energy needed to change from liquid to gas at its boiling point. Latent heat of vaporization is typically much larger than latent heat of fusion because overcoming the intermolecular forces in a liquid requires more energy than breaking the rigid structure of a solid.

34. What is the triple point of a substance, and why is it important?

The triple point is the unique combination of temperature and pressure at which a substance can exist simultaneously in solid, liquid, and gas phases in equilibrium. It's important because it represents a fixed point on the phase diagram and is used to define temperature scales. For example, the triple point of water (273.16 K and 611.2 Pa) is used to define the Kelvin temperature scale.

35. Why does the temperature of a substance remain constant during a phase change?

During a phase change, the temperature remains constant because the added or removed energy is used to change the substance's state rather than increase or decrease its temperature. This energy, called latent heat, goes into breaking or forming intermolecular bonds without changing the kinetic energy of the particles, which determines temperature.

36. What is the difference between intensive and extensive properties in the context of phase changes?

Intensive properties, such as melting point and boiling point, do not depend on the amount of substance and remain constant during phase changes. Extensive properties, like the total heat absorbed or released during a phase change, depend on the amount of substance. Understanding this distinction is crucial for calculations involving heat transfer and phase transitions.

37. How do intermolecular forces affect the properties of different states of matter?

Intermolecular forces determine many properties of substances in different states. Stronger forces result in higher melting and boiling points, greater surface tension in liquids, and less compressibility in solids and liquids. Weaker forces lead to lower melting and boiling points, easier vaporization, and greater compressibility, as seen in gases.

38. Why do some materials become brittle when cooled while others become more flexible?

The brittleness or flexibility of materials when cooled depends on their molecular structure and intermolecular forces. Materials that become brittle, like ceramics or some metals, have strong, directional bonds that restrict molecular movement when cooled. Materials that become more flexible, like rubber, have long, coiled molecules that can still move relative to each other at lower temperatures, maintaining flexibility.

39. How does the concept of vapor pressure relate to phase changes?

Vapor pressure is the pressure exerted by a vapor in equilibrium with its liquid or solid phase at a given temperature. As temperature increases, vapor pressure increases. Boiling occurs when the vapor pressure equals the atmospheric pressure. Understanding vapor pressure helps explain phenomena like why liquids evaporate faster at higher temperatures or lower atmospheric pressures.

40. What is the significance of the heat of vaporization in everyday life?

The heat of vaporization is crucial in many everyday phenomena. It explains why sweating cools us (as sweat evaporates, it removes heat from our skin), why steam burns are more severe than hot water burns (steam releases its heat of vaporization when condensing on skin), and why evaporative cooling is used in refrigeration and air conditioning systems.

41. How do phase changes affect the density of a substance?

Phase changes typically alter a substance's density. Most substances become less dense as they change from solid to liquid to gas, as particles move farther apart. Water is a notable exception; it expands when freezing, making ice less dense than liquid water. Understanding these density changes is crucial in fields like geology, meteorology, and engineering.

42. How do phase diagrams help us understand the behavior of substances under different conditions?

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.

43. How do nanomaterials exhibit different melting and boiling points compared to bulk materials?

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.

44. Why do some substances, like dry ice, sublimate at atmospheric pressure?

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.

45. What is the role of nucleation in phase changes, particularly in crystallization and boiling?

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.

46. How do pressure cookers utilize the relationship between pressure and boiling point?

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.

47. What is the difference between an amorphous solid and a crystalline solid in terms of phase transitions?

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.

48. How do phase changes in water affect climate and weather patterns?

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.

49. Why do some materials expand when they freeze while others contract?

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.

50. What is the role of pressure in determining the state of matter for a given substance?

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.

51. How do eutectic mixtures affect the melting and freezing behavior of substances?

Eutectic mixtures are combinations of substances that have a lower melting point than either of the pure components. At the eutectic composition, the mixture melts and freezes at a single temperature, behaving like a pure substance. This property is used in creating low-melting alloys, de-icing solutions, and in some phase-change materials for energy storage.

52. What is the significance of the glass transition in amorphous solids?

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.