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Filtration
Filtration separates by particle size. The residue is the solid left on the filter. The filtrate is the liquid that goes through. Gravity filtration uses filter paper in a funnel. Vacuum filtration uses a Buchner funnel to pull liquid through faster.
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Filtration
What is it?
Filtration separates by particle size. The residue is the solid left on the filter. The filtrate is the liquid that goes through. Gravity filtration uses filter paper in a funnel. Vacuum filtration uses a Buchner funnel to pull liquid through faster.
In simple words
- Filtration separates by particle size.
- The residue is the solid left on the filter.
- To separate sand and sugar: dissolve the sugar in water, filter off the sand (residue), then evaporate or crystallise the sugar from the filtrate.
- Heterogeneous sand-water can be filtered.
Important terms
particle size: Filtration separates by particle size.
residue: Filtration separates by particle size.
filtrate: Filtration separates by particle size.
Gravity: Filtration separates by particle size.
filter paper: Filtration separates by particle size.
What you should learn
- State the main idea of filtration in clear words.
- Explain why filtration is useful in chemistry.
- Apply the correct method, observation, equation, or comparison.
- Avoid the common mistakes and write a complete exam answer.
Examples
- Sand on the paper
- Sugar water through
- Sugar crystals later
SAND AND SUGAR
To separate sand and sugar: dissolve the sugar in water, filter off the sand (residue), then evaporate or crystallise the sugar from the filtrate. The sand never dissolves, so it stays on the paper.
WHAT WILL NOT FILTER
Heterogeneous sand-water can be filtered. Homogeneous brine cannot: the salt is dissolved, so it passes through with the water. Filtration needs a solid that is bigger than the holes in the paper.
Recommended for Class 9
Full school-level explanation
Filtration separates by particle size. The residue is the solid left on the filter. The filtrate is the liquid that goes through. Gravity filtration uses filter paper in a funnel. Vacuum filtration uses a Buchner funnel to pull liquid through faster.
What filtration can and cannot do:
WHAT — Core idea
Filtration separates by particle size. The residue is the solid left on the filter. The filtrate is the liquid that goes through. Gravity filtration uses filter paper in a funnel. Vacuum filtration uses a Buchner funnel to pull liquid through faster.
WHY — Why it matters
Name both products in an exam answer: residue on the paper, filtrate in the flask. Vacuum with a Buchner funnel is the same idea as gravity, only faster.
HOW — Method, evidence, or comparison
1. 1. SAND AND SUGAR: To separate sand and sugar: dissolve the sugar in water, filter off the sand (residue), then evaporate or crystallise the sugar from the filtrate. The sand never dissolves, so it stays on the paper. 2. 2. WHAT WILL NOT FILTER: Heterogeneous sand-water can be filtered. Homogeneous brine cannot: the salt is dissolved, so it passes through with the water. Filtration needs a solid that is bigger than the holes in the paper.
HOW — Answer in an exam
You cannot filter dissolved salt from brine. First evaporate or distil if you need the solid or the water.
SAND AND SUGAR
To separate sand and sugar: dissolve the sugar in water, filter off the sand (residue), then evaporate or crystallise the sugar from the filtrate. The sand never dissolves, so it stays on the paper.
Remember
- dissolve
- filter
- evaporate
- crystallise
Examples
- Sand on the paper
- Sugar water through
- Sugar crystals later
WHAT WILL NOT FILTER
Heterogeneous sand-water can be filtered. Homogeneous brine cannot: the salt is dissolved, so it passes through with the water. Filtration needs a solid that is bigger than the holes in the paper.
Remember
- Heterogeneous
- Homogeneous brine
- dissolved
Examples
- Sand-water: yes
- Chalk-water: yes
- Salt water: no
Remember
- particle size
- residue
- filtrate
- Gravity
- filter paper
- vacuum
- Buchner
- residue
How the ideas connect
Name both products in an exam answer: residue on the paper, filtrate in the flask. Vacuum with a Buchner funnel is the same idea as gravity, only faster.
Deeper understanding
Go beyond memorising Filtration. Connect the definition to reasons, relationships, exceptions, and exam wording.
How the ideas connect
Name both products in an exam answer: residue on the paper, filtrate in the flask. Vacuum with a Buchner funnel is the same idea as gravity, only faster.
Common mistakes
Exam focus
WHAT
Key Points
HOW
Example
Exam focus
Quick revision
- particle size
- residue
- filtrate
- Gravity
- particle size: Filtration separates by particle size.
- residue: Filtration separates by particle size.
You cannot filter dissolved salt from brine. First evaporate or distil if you need the solid or the water.
For long answers on Filtration: define clearly → explain the main parts → give one example → state one exam caution.
Exam Focus
Exam Focus
Important points
- particle size
- residue
- filtrate
- Gravity
Important formulas
- particle size
- residue
- filtrate
Common exam traps
- Residue stays on the paper; filtrate passes through it.
- Dissolved salt passes through filter paper with the water.
Long question structure
Definition → key parts → example → exam caution
Common Mistakes
Common Mistakes
- Mistake
Residue stays on the paper; filtrate passes through it.
- Mistake
Dissolved salt passes through filter paper with the water.
- Mistake
You cannot filter dissolved salt from brine. First evaporate or distil if you need the solid or the water.
Revision Zone
60-Second Revision
Quick cues from this topic — use them for last-minute revision.
particle size
residue
filtrate
Gravity
Filtration separates by particle size. The residue is the solid left on the filter. The filtrate is the liquid that goes through. Gravity filtration uses filter
- Definition
- Filtration separates by particle size. The residue is the solid left on the filter. The filtrate is the liquid that goes through. Gravity filtration uses filter
- Example
- Sand on the paper
- Critical warning
- Residue stays on the paper; filtrate passes through it.
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Exam Practice
Define
Q1. Define Filtration.
Explain
Q2. Explain: SAND AND SUGAR.
Example
Q3. Give one clear example of Filtration and say why it fits.
Mistake
Q4. State one common mistake students make about Filtration.
Exam note
Q5. Write a short exam note on Filtration: definition, two points, one example.
Sources & References
School-standard facts for Matric and Intermediate. Original explanations — not copied from textbooks.