Edexcel A-Level Chemistry A2 6 P18 Preparing Inorganic and Organic Compounds Topic Practice

A group of students prepared methyl 3-nitrobenzoate by the nitration of methyl benzoate.

Procedure

Step 1 Measure $9 \mathrm{~cm}^{3}$ of concentrated sulfuric acid into a small, dry conical flask. Label the flask A and place it in an ice bath.

Step 2 Add $4.0 \mathrm{~cm}^{3}$ of methyl benzoate to flask A.
Gently swirl the flask.
Step 3 Mix $3 \mathrm{~cm}^{3}$ of concentrated nitric acid and $3 \mathrm{~cm}^{3}$ of concentrated sulfuric acid in a test tube to form the nitrating mixture. Place this test tube in the ice bath.

Step 4 Place a thermometer in flask A. Add the nitrating mixture very slowly to flask A using a dropping pipette.
Take care to ensure that the temperature of the flask contents does not rise above $15^{\circ} \mathrm{C}$.

Step 5 Remove flask A from the ice bath and allow it to stand at room temperature for about 10 minutes.
Pour the reaction mixture into a small beaker containing crushed ice. Stir the contents of the beaker with a glass rod.

Step 6 Allow the ice to melt. Separate the solid methyl 3-nitrobenzoate by suction filtration. Wash the solid with a small amount of deionised water and then with a little ice-cold ethanol.

Step 7 Recrystallise the methyl 3-nitrobenzoate using ethanol as the solvent.
Step 8 Determine the melting temperature of the purified crystals of methyl 3-nitrobenzoate.

An ice bath is a mixture of ice and water in a beaker.

Suggest an advantage of using an ice bath in Steps 1 and 3 rather than a beaker containing only ice cubes. Justify your answer.