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Question
Name two ways of change of liquid state to the vapour state and distinguish them.
Solution
Two ways of change of liquid state to vapour state are:
- Evaporation
- Boiling.
DIFFERENCE BETWEEN EVAPORATION AND BOILING:
| BOILING | EVAPORATION |
|
(1) Heat is supplied. |
Heat is absorbed. |
| (2) Fast process. | Slow process. |
| (3) Starts from the bottom. | Starts form surface i.e. |
| (4) Sound is produced. | surface phenomenon Silent process. |
| (5) Heating effect | Cooling effect |
| (6) Takes place at a fixed temperature called the boiling point. | Takes place at all temperatures. |
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RELATED QUESTIONS
Evaporation takes place only from the surface of liquid.
Temperature of a liquid rises during boiling or vaporization
Boiling occurs at ....................
The molecules of liquid ............. heat from surroundings in evaporation.
Match the column
| Column A | Column B |
| (a) Blowing air increases | (1) Increase in intermolecular separation |
| (b) Increase in pressure increases | (2) Pendulum of a clock |
| (c) Thermal expansion |
(3) Cooking utensils |
| (d) Invar | (4) Boiling point |
| (e) Pyrex glass | (5) Evaporation |
In evaporation
The rate of evaporation of a liquid increases when:
No heat is supplied to a liquid during evaporation. How does then the liquid change into its vapours?
Why is cooling produced when a liquid evaporates?
What is boiling? Explain it on the basis of molecular motion?
