A reaction vessel of negligible heat capacity held 75 cm³ of 1.0 M HCl solution at a temperature of 13.0 °C - Leaving Cert Chemistry - Question 3 - 2013

Polystyrene or other suitable insulating materials such as plastic or cardboard should be used as they minimize heat transfer to the environment.

(i) One advantage of using a burette is that it allows for more precise delivery of the reactant, enabling more accurate measurements. (ii) One disadvantage is that a burette may be more difficult to read accurately compared to a graduated cylinder, particularly if the level of the liquid is very close to a graduation line.

1. Use a sensitive thermometer that can read to at least 0.2 °C, ensuring it is properly calibrated.
2. Minimize external influences by covering the reaction vessel to prevent heat loss and ensuring the thermometer is not exposed to air drafts during measurements.

To calculate the moles of HCl, we can use the formula:

$n = C imes V$

Where:

• $C$ = concentration in mol/L = 1.0 M
• $V$ = volume in L = 0.075 L (75 cm³ converted to liters)

Hence, $n = 1.0 imes 0.075 = 0.075 ext{ mol}$

Using the formula for heat transfer:

$q = mc heta$

Where:

• $m$ = mass of the solution = 75 g (since the density of solution is 1 g/cm³)
• $c$ = specific heat capacity = 4.2 J/g°C
• $heta$ = change in temperature = 20.9 °C - 13.0 °C = 7.9 °C

Hence, $q = 75 imes 4.2 imes 7.9 = 2,478.75 ext{ J} = 2.48 ext{ kJ}$

To calculate the heat of reaction per mole of HCl:

Hydrochloric acid is corrosive and can cause burns to the skin and eyes. Sodium hydroxide is also corrosive and can cause severe damage to skin and eyes upon contact.

To label the two solutions, proper labeling should be done before the experiment includes the correct concentration, compound name, and hazard symbols. If 0.1 M solutions were used, the problem would be that the reaction would be slower and may not reach measurable heat changes, leading to inaccurate results.