Short Answer

Melting is the process in which a solid changes into a liquid when heat is supplied. During melting, the solid absorbs heat, and its particles gain energy. This energy allows the particles to break free from their fixed positions, making the solid turn into a liquid. Every solid has a specific temperature at which it melts, known as its melting point.

A common example of melting is ice turning into water when kept outside a freezer or when heated. Melting is a reversible physical change because the liquid can become solid again on cooling. It does not produce a new substance.

Detailed Explanation :

Melting

Melting is an important physical change in which a substance changes its state from solid to liquid upon heating. This change occurs because heat energy is absorbed by the solid, causing the particles to move faster and overcome the strong forces of attraction holding them together. When the solid reaches a specific temperature called the melting point, it begins to change into a liquid.

Melting is a reversible process, meaning the liquid formed can be cooled again to become a solid. During melting, only the physical form of matter changes; the chemical composition remains the same. For example, ice and water are the same substance—both are made of H₂O molecules.

Melting is a part of the interconversion of states of matter and is commonly observed in daily life. It helps us understand how temperature affects particle arrangement and movement.

How Melting Occurs

1. Heating the Solid

The melting process starts when heat is supplied to a solid. Solids have tightly packed particles held together by strong forces of attraction. When heat is added:

• The particles absorb energy.
• They vibrate faster.
• Their kinetic energy increases.

As the temperature increases, the particles vibrate so much that they start to overcome the strong forces binding them.

2. Breaking of Intermolecular Forces

As more heat is absorbed, the vibration becomes strong enough to weaken the intermolecular forces. These forces hold the particles in fixed positions. When the forces become weak:

• The particles begin to move out of their fixed positions.
• The solid structure starts to break down.
• The solid begins melting.

This transition from fixed arrangement to free movement is the key to melting.

3. Melting Point

The temperature at which a solid changes into a liquid is called its melting point. Every solid has a specific melting point. Some examples include:

• Ice melts at 0°C.
• Wax melts around 60°C.
• Iron melts at 1538°C.

At the melting point, heat energy is used to change the state rather than increasing the temperature. This is why ice stays at 0°C while melting.

4. Liquid Formation

Once the particles break free from their fixed positions, the solid turns into a liquid. In the liquid state:

• Particles are still close but not in fixed positions.
• They can slide past one another.
• They have more freedom to move compared to solids.

This change in particle behavior explains the flowing nature of liquids.

5. Energy Changes During Melting

Melting involves absorption of heat energy. This energy is used to break the strong forces of attraction in solids. The temperature remains constant during melting because the energy is used for the state change, not for heating.

Examples of Melting in Daily Life

Melting is seen in many common activities:

• Ice turning into water on a warm day
• Butter melting on a hot pan
• Wax melting during burning of a candle
• Chocolate melting when held in the hand
• Metal melting in factories to mold into shapes

These examples show how heat changes the state of solids.

Factors Affecting Melting

Several factors influence how easily a solid melts:

• Nature of the material: Substances with strong intermolecular forces have higher melting points.
• Purity: Impurities lower the melting point (e.g., salt lowers ice’s melting point).
• Pressure: Generally, pressure has little effect on melting, except in some special cases like ice.

Melting as a Physical Change

Melting is a physical change because:

• No new substance is formed.
• Only the state changes; the composition remains the same.
• It can be reversed by cooling (liquid → solid).

This shows that melting does not alter the chemical identity of the substance.

Conclusion

Melting is the process where a solid changes into a liquid when heat is supplied. It occurs because heat energy weakens the intermolecular forces and allows particles to move freely. Melting happens at a specific temperature called the melting point and is a reversible physical change. This process helps us understand how temperature affects matter and is observed commonly in everyday life.