Melting
Changes of State: Melting
Melting
Melting: Solid to Liquid
What you'll learn
- Define melting and identify the melting point.
- Give examples of solids that melt on heating.
- Explain that melting is a reversible change.
- Connect melting to everyday Indian examples.
Key concepts
Level 1 - Meaning of melting
Melting is the change of a solid into a liquid when it is heated. Ice melting into water and butter melting in a warm pan are both common examples of melting.
Level 2 - Melting point
Every solid has its own melting point, the temperature at which it starts turning into a liquid. Ice melts at 0 degrees Celsius, while metals like iron need extremely high heat before they melt.
Level 3 - Melting is reversible
When a melted liquid is cooled again, it can turn back into a solid. Melted candle wax hardens back into solid wax once it cools, showing that melting can be reversed by freezing.
Level 4 - Indian context
On a hot summer afternoon, ice kept outside a freezer melts quickly into water. Kulfi and ice cream sold on the streets can start melting fast in the summer heat if not kept in a cooler.
NCERT anchor: Looking Around 4, general observation of heating and changes in materials (melting of ice, butter, wax)
Worked example
Melting an ice cube
Step 1 - Place an ice cube in a bowl at room temperature.
Step 2 - Watch it for several minutes.
Step 3 - Observe the solid ice slowly turning into liquid water.
Step 4 - Touch the bowl; it now holds only water, no ice.
Answer: The ice cube has melted, changing from a solid into a liquid.
Melting butter in a hot pan
Step 1 - Place a small piece of solid butter in a hot pan.
Step 2 - Heat the pan gently on a stove.
Step 3 - Observe the butter turning shiny and runny.
Step 4 - The butter can now be poured like a liquid.
Answer: Heat melted the solid butter into a liquid.
Common mistakes
| Mistake | Why it happens | Fix |
|---|---|---|
| Melting and dissolving are the same | Both make a solid seem to change form | Melting needs heat and no solvent; dissolving needs a liquid solvent like water and no heat is required |
| All solids melt at the same temperature | Ice melts easily, so all solids seem the same | Different solids have different melting points; metals need much higher heat than ice |
| Melting is a change that cannot be undone | Melted material looks completely different | Melting is reversible: cooling a melted liquid can freeze it back into a solid |
| A solid must be very hot to start melting | Ice melts even in a cool room | A solid melts once it reaches its own melting point, which can be low, like 0 degrees Celsius for ice |
Quick check
- What is melting?
- What is the melting point of ice?
- Give one example of a solid melting at home.
- Is melting reversible? Explain with an example.
- Stretch: Explain why a metal spoon does not melt in hot tea but an ice cube does.
Revision tip: Melting turns a solid into a liquid when it is heated to its melting point.
Open the Practice tab for graded questions on Melting.
Key Takeaways (TL;DR)
- What you'll learn
- Key concepts
- Worked example
- Common mistakes
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