Core Practical 14 Lab

Aim

To use the Arrhenius equation to determine the activation energy of a reaction

Equipment

70 cm3 of 0.01 mol dm−3 aqueous phenol solution ● 70 cm3 bromide/bromate solution ● 50 cm3 of 0.5 mol dm−3 sulfuric acid ● methyl red indicator ● three 100 cm3 beakers ● 2 boiling tubes ● 10 cm3 pipette ● thermometer (0–110 °C) ● stop clock ● 500 cm3 beaker ● access to a kettle

1. Pipette 10 cm3 of phenol solution and 10 cm3 of bromide/bromate solution into one boiling tube.

2. Add four drops of methyl red indicator to the mixture.

3. Pipette 5 cm3 of sulfuric acid solution into another boiling tube.

4. Use a kettle and a beaker to prepare a water bath with a temperature of 75 °C (±1 °C). Stand the two boiling tubes in the water bath.

5. When the contents of the boiling tubes have reached the water temperature, mix the contents of the two tubes by pouring rapidly from one tube into the other and then pouring the mixture back into the empty test tube. Start the stop clock at the same time.

6. Leave the boiling tube containing the reaction mixture in the water and time until the methyl red indicator disappears.

7. Copy the results table below and use the first two columns to record all your results.

8. Repeat the whole experiment at 65 °C, 55 °C, 45 °C, 35 °C, 25 °C and 15 °C. Use ice to achieve the lowest temperature.