Chem Paper 3 flashcards

Explain why the product (more stable carbocation) shown in your answer to Question 2.2 is the major product. [2 marks]

Allows reactant vapours (of volatile organic compounds) to be returned to the reaction mixture / does not allow any reactant vapour to escape

Suggest why sodium benzoate is soluble in cold water but benzoic acid is insoluble in cold water. [2 marks]

• Sodium benzoate soluble because it is ionic

• Benzoic acid insoluble because: despite the polarity of the COOH group / ability of COOH to form H-bonds, the benzene ring is non-polar.

After the solid benzoic acid has been filtered off, it can be purified.

Describe the method that the student should use to purify the benzoic acid. [6 marks]

• Dissolve crude product in hot solvent/water

• of minimum volume

• Filter (hot to remove insoluble impurities)

• Cool to recrystallise

• Filter under reduced pressure / with Buchner/Hirsch apparatus

• wash (with cold solvent) and dry

C

D

C

D