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Distillation
Distillation means vaporise then condense. The distillate is the collected liquid. A liquid boils when its vapour pressure equals the external P. Heat the flask; the lowest boiling point (BP) substance leaves first; a condenser cools the vapour back to liquid.
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Distillation
What is it?
Distillation means vaporise then condense. The distillate is the collected liquid. A liquid boils when its vapour pressure equals the external P. Heat the flask; the lowest boiling point (BP) substance leaves first; a condenser cools the vapour back to liquid.
In simple words
- Distillation means vaporise then condense.
- The distillate is the collected liquid.
- Heat raises vapour pressure until it matches the outside pressure.
- The condenser cools vapour so it becomes liquid again.
Important terms
vaporise: Distillation means vaporise then condense.
condense: Distillation means vaporise then condense.
distillate: Distillation means vaporise then condense.
vapour pressure: Distillation means vaporise then condense.
external P: Distillation means vaporise then condense.
What you should learn
- State the main idea of distillation in clear words.
- Explain why distillation is useful in chemistry.
- Apply the correct method, observation, equation, or comparison.
- Avoid the common mistakes and write a complete exam answer.
Examples
- Water leaving salt
- Alcohol leaving water
- Light oil leaving crude
IN THE FLASK
Heat raises vapour pressure until it matches the outside pressure. The liquid then boils. The substance with the lowest BP turns to vapour first. Keep the thermometer where the vapour leaves, not in the liquid, if you are reading BP.
IN THE CONDENSER
The condenser cools vapour so it becomes liquid again. That liquid is the distillate. Cold water usually runs in the jacket. Forms of distillation have been known since ancient civilisations (around 3000 BC).
Recommended for Class 9
Full school-level explanation
Distillation means vaporise then condense. The distillate is the collected liquid. A liquid boils when its vapour pressure equals the external P. Heat the flask; the lowest boiling point (BP) substance leaves first; a condenser cools the vapour back to liquid.
The flask and the condenser do different jobs:
WHAT — Core idea
Distillation means vaporise then condense. The distillate is the collected liquid. A liquid boils when its vapour pressure equals the external P. Heat the flask; the lowest boiling point (BP) substance leaves first; a condenser cools the vapour back to liquid.
WHY — Why it matters
Distillation is vaporise + condense, not just heating. If you only boil and do not collect, you have evaporation, not distillation.
HOW — Method, evidence, or comparison
1. 1. IN THE FLASK: Heat raises vapour pressure until it matches the outside pressure. The liquid then boils. The substance with the lowest BP turns to vapour first. Keep the thermometer where the vapour leaves, not in the liquid, if you are reading BP. 2. 2. IN THE CONDENSER: The condenser cools vapour so it becomes liquid again. That liquid is the distillate. Cold water usually runs in the jacket. Forms of distillation have been known since ancient civilisations (around 3000 BC).
HOW — Answer in an exam
Boiling is not a random hot moment. It is the point where vapour pressure = external P. Lower the outside pressure and the BP falls (vacuum distillation).
IN THE FLASK
Heat raises vapour pressure until it matches the outside pressure. The liquid then boils. The substance with the lowest BP turns to vapour first. Keep the thermometer where the vapour leaves, not in the liquid, if you are reading BP.
Remember
- vapour pressure
- lowest BP
Examples
- Water leaving salt
- Alcohol leaving water
- Light oil leaving crude
IN THE CONDENSER
The condenser cools vapour so it becomes liquid again. That liquid is the distillate. Cold water usually runs in the jacket. Forms of distillation have been known since ancient civilisations (around 3000 BC).
Remember
- condenser cools
- distillate
- ancient civilisations
- 3000 BC
Examples
- Water from seawater
- Solvent recovery
- Early stills for oils
Remember
- vaporise
- condense
- distillate
- vapour pressure
- external P
- lowest
- BP
- condenser
How the ideas connect
Distillation is vaporise + condense, not just heating. If you only boil and do not collect, you have evaporation, not distillation.
Deeper understanding
Go beyond memorising Distillation. Connect the definition to reasons, relationships, exceptions, and exam wording.
How the ideas connect
Distillation is vaporise + condense, not just heating. If you only boil and do not collect, you have evaporation, not distillation.
Common mistakes
Exam focus
WHAT
Key Points
HOW
Example
Exam focus
Quick revision
- vaporise
- condense
- distillate
- vapour pressure
- vaporise: Distillation means vaporise then condense.
- condense: Distillation means vaporise then condense.
Boiling is not a random hot moment. It is the point where vapour pressure = external P. Lower the outside pressure and the BP falls (vacuum distillation).
For long answers on Distillation: define clearly → explain the main parts → give one example → state one exam caution.
Exam Focus
Exam Focus
Important points
- vaporise
- condense
- distillate
- vapour pressure
Important formulas
- vaporise
- condense
- distillate
Common exam traps
- Distillation includes both vaporising and condensing.
- The distillate is the liquid collected after condensation, not the material left in the flask.
Long question structure
Definition → key parts → example → exam caution
Common Mistakes
Common Mistakes
- Mistake
Distillation includes both vaporising and condensing.
- Mistake
The distillate is the liquid collected after condensation, not the material left in the flask.
- Mistake
Boiling is not a random hot moment. It is the point where vapour pressure = external P. Lower the outside pressure and the BP falls (vacuum distillation).
Revision Zone
60-Second Revision
Quick cues from this topic — use them for last-minute revision.
vaporise
condense
distillate
vapour pressure
Distillation means vaporise then condense. The distillate is the collected liquid. A liquid boils when its vapour pressure equals the external P. Heat the flask
vapour pressure = external P
- Definition
- Distillation means vaporise then condense. The distillate is the collected liquid. A liquid boils when its vapour pressure equals the external P. Heat the flask
- Formula
- vapour pressure = external P
- Example
- Water leaving salt
- Critical warning
- Distillation includes both vaporising and condensing.
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Exam Practice
Define
Q1. Define Distillation.
Explain
Q2. Explain: IN THE FLASK.
Example
Q3. Give one clear example of Distillation and say why it fits.
Mistake
Q4. State one common mistake students make about Distillation.
Exam note
Q5. Write a short exam note on Distillation: definition, two points, one example.
Sources & References
School-standard facts for Matric and Intermediate. Original explanations — not copied from textbooks.