Sodium hydroxide is reacted with hydrochloric acid.
NaOH(aq)+HCl(aq)→NaCl(aq)+H2O(l)
20.0 cm3 of 2.00 mol dm-3 sodium hydroxide is measured using a pipette and placed into a polystyrene cup. The temperature of the solution is taken every minute for 3 minutes. On the fourth minute, 25.0 cm3 of 2.00 mol dm-3 hydrochloric acid is added to the polystyrene cup. The temperature of the mixture is taken at 1-minute intervals until 12 minutes have passed in total. The results are recorded in the table.