To oxidise phenylmethanol to benzoic acid with potassium permanganate solution in alkaline conditions 2015

Question 1

Describe the appearance of phenylmethanol at room temperature.

Answer 1

Colourless liquid

Question 2

State color change when phenylmethanol was heated gently with potassium
manganate(VIl) solution to which sodium carbonate had been added.

Answer 2

Purple to brown

Question 3

Identify two substances added to the reaction mixture after heating. State both of their
uses.

Answer 3

HCI: Converts sodium benzoate to benzoic acid and an acidic medium is best to enable Mn4+ into
Mn2+
Sodium sulfite: Reducing agent for Mn4+ to Mnz+

Question 4

What changes were observed in the reaction vessel on addition of these two chemicals and
as cooling occurred?

Answer 4

Muddy brown colour becomes colourless and forms white crystals.

Question 5

State the changes in oxidation of manganese during the experiment.

Answer 5

+7 t0 +4

+4 to +2

Question 6

Benzyl alcohol( phenylmethanol) chemical formula

Answer 6

C7H8O