Temperature Change GCSE Chemistry Practical

Investigate the variables that affect temperature change in chemical reactions.

In this required practical, students are assessed on their ability to measure, record and plot the temperature changes occurring in a chemical reaction. They are to do this by reacting Sodium Hydroxide and Hydrochloric Acid. They will produce a graph of their results and draw two lines of best fit to identify the intersection point. The students use of equipment and chemicals in a safe manner is also observed during the practical session.

Equipment (per participant)

• Safety goggles
• Insulated cups
• 250ml beaker
• Thermometers
• 50ml measuring cylinder
• Hydrochloric Acid (2M)
• Sodium Hydroxide (2M)
• CLEAPSS Hazcards: 47A, 91A

Method

Setup and Preparation

Collect Equipment

Gather all necessary equipment, including an insulated cup, 250ml beaker, measuring cylinder, thermometer, Hydrochloric Acid, Sodium Hydroxide, and a lid or a small square of cardboard.

Stabilise the Insulated Cup

Place the insulated cup inside a 250ml beaker to improve its stability during the experiment.

Conducting the Experiment

Prepare the Hydrochloric Acid

Measure 30ml of Hydrochloric Acid using the measuring cylinder.
Carefully pour the acid into the insulated cup.
Rinse the measuring cylinder thoroughly with water.

Record the Starting Temperature

Use a thermometer to measure the starting temperature of the acid.
Record this value in a suitable data table.

Add Sodium Hydroxide in Steps

Measure 5ml of Sodium Hydroxide using the measuring cylinder and pour it into the insulated cup.
Fit the cup with a lid (or a piece of cardboard with a hole). Insert the thermometer through the hole so it can also be used as a stirrer.

Monitor and Record Temperature

Stir the solution gently with the thermometer.
Observe the temperature rise, and once the thermometer reading stabilises, record the maximum temperature reached.

Repeat the Additions

Add another 5ml of Sodium Hydroxide, repeat the stirring, and record the maximum temperature after stabilisation.
Continue this process in 5ml increments until a total of 40ml of Sodium Hydroxide has been added.

Repeating and Analysing

Repeat the Experiment

Wash all equipment thoroughly.
Repeat the entire experiment for a second trial to ensure reliability.

Calculate the Averages

For each addition of Sodium Hydroxide, calculate the mean maximum temperature by averaging the results from both trials.

Technician tips

Lids for the insulated cups could be made using a small square of cardboard. A hole can be made through the cardboard, using a sharp pencil, through which a thermometer can be inserted. These could be pre-made for students to save time during the practical session.
Polystyrene cups are no longer widely available to purchase. Schools can re-use these where possible until the end of their supply is reached. An insulated paper drinks cup is a good replacement for use during this practical.