Oxidation of Phenylmethanol

Describe the appearance of phenylmethanol at room temperature.

• colourless pale liquid

• clear pale liquid

• colourless pale solid

• clear pale solid

Name a suitable piece of apparatus to measure accurately 1.5 cm³ of phenylmethanol.

• pipette

• dropper

• burette

• syringe

• all of the above

The oxidation of phenylmethanol is carried out by which of the following oxidising agents?

• Potassium Permanganate

• Hydrogen Peroxide

• Potassium Nitrate

• Iodine

Which of the following is the colour change when phenylmethanol was heated gently with potassium manganate(VII) solution to which sodium carbonate had been added.

• Purple to Brown

• Brown to Purple

• Purple to Colourless

• Colourless to Brown

Why is the potassium permanganate solution saturated?

• To ensure sufficient is present to oxidise all the phenymethanol completely to benzoic acid.

• To ensure sufficient is present to reduce all the phenymethanol completely to benzoic acid.

• To ensure it is the limiting reagent.

• To ensure that manganese is reduced from Mn⁷⁺ to Mn²⁺ throughout the experiment.

Why is sodium carbonate necessary?

• To ensure the solution is alkaline, as this oxidation works best at an alkaline pH.

• To ensure the solution is acidic, as this oxidation works best at an acidic pH.

• To ensure the solution is neutral, as this oxidation works best at a neutral pH.

Why is sodium carbonate necessary?

• To ensure the solution is alkaline, as this oxidation works best at an alkaline pH.

• To ensure the solution is acidic, as this oxidation works best at an acidic pH.

• To ensure the solution is neutral, as this oxidation works best at a neutral pH.

Why is hydrochloric acid added?

• To provide protons to convert sodium benzoate to benzoic acid.

• To neutralise the excess sodium carbonate added and potassium hydroxide produced in the reaction.

• To provide an acidic medium to enable sodium sulphite to reduce Mn⁴⁺ to Mn²⁺.

• All of the above.

Why is the conical flask cooled before the addition of hydrochloric acid?

• As a safety precaution.

• Hydrochloric acid works best at cooler temperatures.

• To ensure the first part of the reaction has gone to completion.

• To slow down the reaction.

Why is glass rod is dipped in the solution and placed on damp blue litmus paper?

• To check for acidity - To ensure all the sodium carbonate has reacted.

• To check for acidity - To ensure all the potassium permanganate has reacted.

• To check for acidity - To ensure all the phenolmethanol has reacted.