7 min read
Running the Chromatogram
Stand the strip so only the bottom 5-6 mm sits in the solvent. The solvent must stay BELOW the spots. Hang the paper so it is not touching the walls. Keep the cylinder closed. Stop when the front is about 1-2 cm from the top. Mark the front immediately, then dry.
Choose Your Level
Running the Chromatogram
What is it?
Stand the strip so only the bottom 5-6 mm sits in the solvent. The solvent must stay BELOW the spots. Hang the paper so it is not touching the walls. Keep the cylinder closed. Stop when the front is about 1-2 cm from the top. Mark the front immediately, then dry.
In simple words
- Stand the strip so only the bottom 5-6 mm sits in the solvent.
- The solvent must stay BELOW the spots.
- Dip only 5-6 mm of paper.
- Do not wait forever.
Important terms
5-6 mm: Stand the strip so only the bottom 5-6 mm sits in the solvent.
BELOW: Stand the strip so only the bottom 5-6 mm sits in the solvent.
not touching the walls: Stand the strip so only the bottom 5-6 mm sits in the solvent.
closed: Stand the strip so only the bottom 5-6 mm sits in the solvent.
1-2 cm from the top: Stand the strip so only the bottom 5-6 mm sits in the solvent.
What you should learn
- State the main idea of running the chromatogram in clear words.
- Explain why running the chromatogram is useful in chemistry.
- Apply the correct method, observation, equation, or comparison.
- Avoid the common mistakes and write a complete exam answer.
Examples
- Solvent below the baseline
- Strip hangs free
- Lid closed
STARTING
Dip only 5-6 mm of paper. If solvent covers the spots, the dyes dissolve into the bulk liquid and the run is wrecked. Leave a gap around the strip so it does not touch the walls, or the solvent will creep sideways. Lid on.
STOPPING
Do not wait forever. When the solvent front is about 1-2 cm from the top, lift the paper. Mark the front immediately: after it dries you cannot see where it stopped. Then let the strip dry before you measure.
Recommended for Class 9
Full school-level explanation
Stand the strip so only the bottom 5-6 mm sits in the solvent. The solvent must stay BELOW the spots. Hang the paper so it is not touching the walls. Keep the cylinder closed. Stop when the front is about 1-2 cm from the top. Mark the front immediately, then dry.
Start rules and stop rules:
WHAT — Core idea
Stand the strip so only the bottom 5-6 mm sits in the solvent. The solvent must stay BELOW the spots. Hang the paper so it is not touching the walls. Keep the cylinder closed. Stop when the front is about 1-2 cm from the top. Mark the front immediately, then dry.
WHY — Why it matters
A closed cylinder keeps the vapour saturating the paper. An open cylinder lets solvent evaporate from the front, so the front may stop or smear. Hang straight: a lean against the glass makes a crooked front.
HOW — Method, evidence, or comparison
1. 1. STARTING: Dip only 5-6 mm of paper. If solvent covers the spots, the dyes dissolve into the bulk liquid and the run is wrecked. Leave a gap around the strip so it does not touch the walls, or the solvent will creep sideways. Lid on. 2. 2. STOPPING: Do not wait forever. When the solvent front is about 1-2 cm from the top, lift the paper. Mark the front immediately: after it dries you cannot see where it stopped. Then let the strip dry before you measure.
HOW — Answer in an exam
Solvent BELOW the spots. Mark the front at once. If the front reaches the top, Rf cannot be measured fairly because the true front is lost.
STARTING
Dip only 5-6 mm of paper. If solvent covers the spots, the dyes dissolve into the bulk liquid and the run is wrecked. Leave a gap around the strip so it does not touch the walls, or the solvent will creep sideways. Lid on.
Remember
- 5-6 mm
- covers the spots
- not touch the walls
Examples
- Solvent below the baseline
- Strip hangs free
- Lid closed
STOPPING
Do not wait forever. When the solvent front is about 1-2 cm from the top, lift the paper. Mark the front immediately: after it dries you cannot see where it stopped. Then let the strip dry before you measure.
Remember
- 1-2 cm from the top
- Mark the front immediately
- dry
Examples
- Front near the top
- Pencil tick on the front
- Dry, then measure
Remember
- 5-6 mm
- BELOW
- not touching the walls
- closed
- 1-2 cm from the top
- Mark the front immediately
- closed cylinder
- Hang straight
How the ideas connect
A closed cylinder keeps the vapour saturating the paper. An open cylinder lets solvent evaporate from the front, so the front may stop or smear. Hang straight: a lean against the glass makes a crooked front.
Deeper understanding
Go beyond memorising Running the Chromatogram. Connect the definition to reasons, relationships, exceptions, and exam wording.
How the ideas connect
A closed cylinder keeps the vapour saturating the paper. An open cylinder lets solvent evaporate from the front, so the front may stop or smear. Hang straight: a lean against the glass makes a crooked front.
Common mistakes
Exam focus
WHAT
Key Points
HOW
Example
Exam focus
Quick revision
- 5-6 mm
- BELOW
- not touching the walls
- closed
- 5-6 mm: Stand the strip so only the bottom 5-6 mm sits in the solvent.
- BELOW: Stand the strip so only the bottom 5-6 mm sits in the solvent.
Solvent BELOW the spots. Mark the front at once. If the front reaches the top, Rf cannot be measured fairly because the true front is lost.
For long answers on Running the Chromatogram: define clearly → explain the main parts → give one example → state one exam caution.
Exam Focus
Exam Focus
Important points
- 5-6 mm
- BELOW
- not touching the walls
- closed
Important formulas
- 5-6 mm
- BELOW
- not touching the walls
Common exam traps
- The solvent level must start below the sample spots.
- Mark the solvent front immediately because it disappears as the paper dries.
Long question structure
Definition → key parts → example → exam caution
Common Mistakes
Common Mistakes
- Mistake
The solvent level must start below the sample spots.
- Mistake
Mark the solvent front immediately because it disappears as the paper dries.
- Mistake
Solvent BELOW the spots. Mark the front at once. If the front reaches the top, Rf cannot be measured fairly because the true front is lost.
Revision Zone
60-Second Revision
Quick cues from this topic — use them for last-minute revision.
5-6 mm
BELOW
not touching the walls
closed
Stand the strip so only the bottom 5-6 mm sits in the solvent. The solvent must stay BELOW the spots. Hang the paper so it is not touching the walls. Keep the c
- Definition
- Stand the strip so only the bottom 5-6 mm sits in the solvent. The solvent must stay BELOW the spots. Hang the paper so it is not touching the walls. Keep the c
- Example
- Solvent below the baseline
- Critical warning
- The solvent level must start below the sample spots.
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Exam Practice
Define
Q1. Define Running the Chromatogram.
Explain
Q2. Explain: STARTING.
Example
Q3. Give one clear example of Running the Chromatogram and say why it fits.
Mistake
Q4. State one common mistake students make about Running the Chromatogram.
Exam note
Q5. Write a short exam note on Running the Chromatogram: definition, two points, one example.
Sources & References
School-standard facts for Matric and Intermediate. Original explanations — not copied from textbooks.