student-blogs/facing-ib-exams-withconfidence/) Revise Review Remember (https://blogs.osc-ib.com/2016/01/ibstudent-blogs/revise-reviewremember/) What to do if your IB results are below expectations (https://blogs.osc-ib.com/2016/01/ib-
We can use acidified potassium dichromate (K2Cr2O7) solution to distinguish between
Planning for IB success
primary, secondary and tertiary alcohols.
As with all the experiments listed on this website,
specific experimental details are not given.
success/) Making the grade – revising English
It is your responsibility to research each method and to carry out a substantial risk
A and Language B subjects
Primary alcohols are oxidised to aldehydes and the carboxylic acids
Secondary alcohols are oxidised to ketones.
Tertiary alcohols cannot be oxidised by the dichromate ions.
subjects/) Five Top Physics Tips
Dichromate ions (Cr2O7 2-) are orange. On reduction Cr 3+ ions are formed which are green.
student-blogs/five-top-physics-tips/) Five Top Maths Tips
Can you write a half equation to show this (Hint: The dichromate solution is acidified).
So you would expect to see the tertiary alcohol remaining an orange colour whilst the
secondary and tertiary alcohols would be oxidised and in doing so, the dichromate ions
Extended Essay research – reading
would be reduced to give a green solution.
between the lines
To distinguish between primary and secondary alcohols you would use either Tollen’s
reagent or Fehlings solution.
The unknown alcohol would first need to be oxidised to either the ketone or the aldehyde.
Tollens or Fehlings would be added. Aldehydes will react. Ketones will not react.
An IB student’s New Year’s resolution
For Tollens reagent, a positive result produces a Silver mirror.
(https://blogs.osc-ib.com/2016/01/ibstudent-blogs/an-ib-students-newyears-resolution/) Engage your brain…use it or lose it! (https://blogs.osc-ib.com/2016/01/ibstudent-blogs/engage-your-brainuse-it-or-lose-it/) ‘The summer of the Extended Essay’ – easy tips to get you ahead (https://blogs.osc-ib.com/2016/01/ibstudent-blogs/the-summer-of-theextended-essay-easy-tips-to-getyou-ahead-2/) Why we need sleep (https://blogs.osc-ib.com/2016/01/ib-
For Fehlings solution, the liquid turns from a deep transparent blue colour to a brick red
Choosing your IB Subjects: Don’t
precipitate. The clip mentions that Glucose is added to Fehlings – this is because Glucose
has an aldehyde group!
(https://blogs.osc-ib.com/2016/01/ibstudent-blogs/choosing-your-ibsubjects-dont-panic/) Before you start the IB Diploma, think about your University Choices (https://blogs.osc-ib.com/2016/01/ibstudent-blogs/before-you-start-the-ibdiploma-think-about-your-universitychoices/) Magical Revision Tips. Part 4. (https://blogs.osc-ib.com/2016/01/ibstudent-blogs/magical-revision-tipspart-4/) Magical Revision Tips. Part 3. (https://blogs.osc-ib.com/2016/01/ibstudent-blogs/magical-revision-tipspart-3/) Magical Revision Tips. Part 2. (https://blogs.osc-ib.com/2016/01/ib-
How could you ensure that a primary alcohol is not further oxidised to a carboxylic acid?
part-2/) Magical Revision Tips. Part 1.
You would carry out the reaction by warming and collecting the vapour using a Lieberg
Goodbye NAVIANCE: What next? Alternative Platforms for International Schools (https://blogs.oscib.com/2018/05/ib-teacherblogs/goodbye-naviance-what-nextThe primary alcohol will have a relatively high boiling point due to hydrogen bonds but the
aldehyde only has dipole – dipole forces so it will evaporate / boil at a much lower
Migration from Venezuela (https://blogs.osc-ib.com/2018/05/ib-
If you wanted to form the carboxylic acid you would need to reflux the mixture of primary
alcohol and dichromate.
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