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Oxidation (dichromate School)
Acidified K2Cr2O7 (orange) is the school oxidant. Primary alcohol -> aldehyde (distil out) -> carboxylic acid (reflux excess). Secondary -> ketone (stops). Tertiary: no easy oxidation (no H on C-OH). Colour orange to green (Cr6+ to Cr3+). Meaning: the product depends on class and on whether you distil or reflux. Tollens later sorts aldehyde from ketone. No illicit oxidation routes. Primary -> alde
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Oxidation (dichromate School)
What is it?
Acidified K2Cr2O7 (orange) is the school oxidant. Primary alcohol -> aldehyde (distil out) -> carboxylic acid (reflux excess). Secondary -> ketone (stops). Tertiary: no easy oxidation (no H on C-OH). Colour orange to green (Cr6+ to Cr3+). Meaning: the product depends on class and on whether you distil or reflux. Tollens later sorts aldehyde from ketone. No illicit oxidation routes. Primary -> aldehyde then carboxylic acid if excess oxidant; secondary -> ketone; tertiary resistant. Primary alcohols need distillation to stop at aldehyde; dichromate colour change should be stated.
In simple words
- Acidified K2Cr2O7 (orange) is the school oxidant.
- 1. PRIMARY: Distil: catch aldehyde before it becomes acid.
- 2. 2 AND 3: Propan-2-ol -> propanone, then stop.
- Exam reminder: Exam primary oxidation: distil: aldehyde (ethanal from ethanol) reflux excess: carboxylic acid (ethanoic) K2Cr2O7 orange -> green
Important terms
OXIDATION (DICHROMATE SCHOOL): Acidified K2Cr2O7 (orange) is the school oxidant.
1. PRIMARY: Distil: catch aldehyde before it becomes acid.
2. 2 AND 3: Propan-2-ol -> propanone, then stop.
What you should learn
- Explain oxidation (dichromate school) in simple chemical language.
- Connect 1. primary with 2. 2 and 3 using equations, observations, or trends where needed.
- Answer a short Federal Board question with the correct terms and a clear reason.
Examples
- Distil aldehyde
- Reflux acid
- Orange -> green
PRIMARY
Distil: catch aldehyde before it becomes acid. Reflux with excess oxidant: acid. Ethanal vs ethanoic from ethanol. Smell names if the book uses them. Acidified K2Cr2O7 orange to green Cr3+ — colour change observation.
2 AND 3
Propan-2-ol -> propanone, then stop. Tert-alcohol: remains, dichromate stays orange (school). Fehling/Tollens negative for ketones. Distillation stops at aldehyde; reflux continues to acid.
Recommended for Class 11
Full school-level explanation
Acidified K2Cr2O7 (orange) is the school oxidant. Primary alcohol -> aldehyde (distil out) -> carboxylic acid (reflux excess). Secondary -> ketone (stops). Tertiary: no easy oxidation (no H on C-OH). Colour orange to green (Cr6+ to Cr3+). Meaning: the product depends on class and on whether you distil or reflux. Tollens later sorts aldehyde from ketone. No illicit oxidation routes. Primary -> aldehyde then carboxylic acid if excess oxidant; secondary -> ketone; tertiary resistant. Primary alcohols need distillation to stop at aldehyde; dichromate colour change should be stated.
Distil vs reflux, then class:
WHAT — OXIDATION (DICHROMATE SCHOOL)
Acidified K2Cr2O7 (orange) is the school oxidant. Primary alcohol -> aldehyde (distil out) -> carboxylic acid (reflux excess). Secondary -> ketone (stops). Tertiary: no easy oxidation (no H on C-OH). Colour orange to green (Cr6+ to Cr3+). Meaning: the product depends on class and on whether you distil or reflux. Tollens later sorts aldehyde from ketone. No illicit oxidation routes. Primary -> aldehyde then carboxylic acid if excess oxidant; secondary -> ketone; tertiary resistant. Primary alcohols need distillation to stop at aldehyde; dichromate colour change should be stated.
WHY — Why this topic matters
OXIDATION (DICHROMATE SCHOOL) is an independent FBISE learning unit because students must use its definitions, conditions, equations, or trends separately in explanations and calculations.
HOW — How it works
PRIMARY: Distil: catch aldehyde before it becomes acid. Reflux with excess oxidant: acid. Ethanal vs ethanoic from ethanol. Smell names if the book uses them. Acidified K2Cr2O7 orange to green Cr3+ — colour change observation. Examples: Distil aldehyde; Reflux acid; Orange -> green. 2 AND 3: Propan-2-ol -> propanone, then stop. Tert-alcohol: remains, dichromate stays orange (school). Fehling/Tollens negative for ketones. Distillation stops at aldehyde; reflux continues to acid. Examples: Ketone; 3 no reaction; Green only if oxidised. Exam primary oxidation: distil: aldehyde (ethanal from ethanol) reflux excess: carboxylic acid (ethanoic) K2Cr2O7 orange -> green
PRIMARY
Distil: catch aldehyde before it becomes acid. Reflux with excess oxidant: acid. Ethanal vs ethanoic from ethanol. Smell names if the book uses them. Acidified K2Cr2O7 orange to green Cr3+ — colour change observation.
Remember
- time in the oxidant
Examples
- Distil aldehyde
- Reflux acid
- Orange -> green
2 AND 3
Propan-2-ol -> propanone, then stop. Tert-alcohol: remains, dichromate stays orange (school). Fehling/Tollens negative for ketones. Distillation stops at aldehyde; reflux continues to acid.
Remember
- H on C-OH needed
Examples
- Ketone
- 3 no reaction
- Green only if oxidised
Remember
- 1 -> al then acid
- 2 -> ketone
- 3 no
- distil vs reflux
- school only
- time in the oxidant
- H on C-OH needed
- 1 -> al then acid
How the ideas connect
Exam primary oxidation: distil: aldehyde (ethanal from ethanol) reflux excess: carboxylic acid (ethanoic) K2Cr2O7 orange -> green
Deeper understanding
Go beyond memorising Oxidation (dichromate School). Connect the definition to reasons, relationships, exceptions, and exam wording.
How the ideas connect
Exam primary oxidation: distil: aldehyde (ethanal from ethanol) reflux excess: carboxylic acid (ethanoic) K2Cr2O7 orange -> green
Common mistakes
Exam focus
Core Idea
1. PRIMARY
2. 2 AND 3
Exam Example
Exam focus
Quick revision
- 1 -> al then acid
- 2 -> ketone
- 3 no
- distil vs reflux
- OXIDATION (DICHROMATE SCHOOL): Acidified K2Cr2O7 (orange) is the school oxidant.
- 1. PRIMARY: Distil: catch aldehyde before it becomes acid.
School dichromate. No chromate waste-dump, no illicit synth.
For long answers on Oxidation (dichromate School): define clearly → explain the main parts → give one example → state one exam caution.
Exam Focus
Exam Focus
Important points
- 1 -> al then acid
- 2 -> ketone
- 3 no
- distil vs reflux
Important formulas
- 1 -> al then acid
- 2 -> ketone
- 3 no
Common exam traps
- Do not confuse 1. PRIMARY with 2. 2 AND 3; state the difference before giving an example.
- Writing only “1 -> al then acid” is not enough. Explain what it means in a complete sentence.
Long question structure
Definition → key parts → example → exam caution
Common Mistakes
Common Mistakes
- Mistake
Do not confuse 1. PRIMARY with 2. 2 AND 3; state the difference before giving an example.
- Mistake
Writing only “1 -> al then acid” is not enough. Explain what it means in a complete sentence.
- Mistake
School dichromate. No chromate waste-dump, no illicit synth.
- Mistake
School dichromate. No chromate waste-dump, no illicit synth.
Revision Zone
60-Second Revision
Quick cues from this topic — use them for last-minute revision.
1 -> al then acid
2 -> ketone
3 no
distil vs reflux
Acidified K2Cr2O7 (orange) is the school oxidant. Primary alcohol -> aldehyde (distil out) -> carboxylic acid (reflux excess). Secondary -> ketone (stops). Tert
- Definition
- Acidified K2Cr2O7 (orange) is the school oxidant. Primary alcohol -> aldehyde (distil out) -> carboxylic acid (reflux excess). Secondary -> ketone (stops). Tert
- Example
- Distil aldehyde
- Critical warning
- Do not confuse 1. PRIMARY with 2. 2 AND 3; state the difference before giving an example.
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Exam Practice
Define
Q1. Define Oxidation (dichromate School).
Explain
Q2. Explain: PRIMARY.
Example
Q3. Give one clear example of Oxidation (dichromate School) and say why it fits.
Mistake
Q4. State one common mistake students make about Oxidation (dichromate School).
Exam note
Q5. Write a short exam note on Oxidation (dichromate School): definition, two points, one example.
Sources & References
School-standard facts for Matric and Intermediate. Original explanations — not copied from textbooks.