The apparatus drawn was used in a student experiment to measure the heat of reaction (ΔH) for the reaction between 1.0 M hydrochloric acid (HCl) solution and 1.0 M sodium hydroxide (NaOH) solution - Leaving Cert Chemistry - Question 3 - 2007

During the experiment, the temperature of the reaction mixture increases, indicating that heat is released. This increase in temperature suggests that the reaction is exothermic, as energy is being transferred from the reaction mixture to the surroundings.

Polystyrene is a good insulator, which minimizes heat loss to the environment during the reaction. This helps in obtaining more accurate temperature readings since it reduces the error due to external temperature changes.

To achieve accurate results, allow temperature equalisation before starting the experiment. Use a calibrated thermometer to measure initial temperatures accurately. Stir the solution thoroughly and quickly record the highest temperature reached to ensure accurate temperature data.

The number of moles can be calculated using the formula:

ext{moles} = rac{ ext{Volume (L)} imes ext{Concentration (mol/L)}}{1}

For 50 cm³ (or 0.050 L) of 1.0 M solution:

$ext{moles} = 0.050 imes 1.0 = 0.05 ext{ moles}$

Given that 2.8 kJ of heat is produced when 0.05 moles of HCl react, the heat produced when 1 mole reacts is calculated as follows:

ext{Heat per mole} = rac{2.8 ext{ kJ}}{0.05 ext{ moles}} = 56 ext{ kJ}

The term used for this reaction is 'neutralisation.' In a neutralisation reaction, an acid reacts with a base to form a salt and water.