Melting Point Benzoic Acid

Give the procedure for finding the melting point of benzoic acid

1. Crystals ground up with pestle and mortar.

2. Placed in capillary tube which is placed into aluminium melting block.

3. Melting block is heated slowly using a hotplate while observing the crystals.

4. The melting point range of the crystals is measured using a thermometer

When is the temperature recorded?

When the crystals begin to melt and when they have finished melting

What is the melting point range of pure benzoic acid crystals?

Sharply at 122C

Give two differences when determining the melting point of impure benzoic acid

melting point lower than 122C

crystals melt over a wider range of temperature

give a use of benzoic acid and its salts

food preservatives