PAG 3.1 Questions and Answers | Latest Update | 2024/2025 | Already Passed

PAG 3.1 Questions and Answers | Latest Update | 2024/2025 | Already Passed **How can you determine the enthalpy change when neutralising HCl with NaOH?** To determine the enthalpy change of neutralisation, start by placing a polystyrene cup inside a glass beaker. Measure 25 cm3 of 1.0 mol/dm3 hydrochloric acid and 25 cm3 of 1.0 mol/dm3 sodium hydroxide. Record the initial temperature and take readings every minute for 4 minutes. At the 4-minute mark, mix the solutions and continue to measure the temperature change. **What equipment is necessary for this experiment?** Safety goggles, a polystyrene cup, a glass beaker, a thermometer, measuring cylinders, dropping pipettes, and a timer/stopwatch are essential equipment. **How do you calculate the energy absorbed by the solution, given a specific heat capacity of 4.18 J/g°C?** Calculate the energy absorbed (q) using the formula q = mass of solution × 4.18 J/g°C × temperature change. **How do you determine the moles of HCl used?** Calculate the moles of HCl (n) using n = concentration (C) × volume (V), where C = 1.0 mol/dm3 and V = 25 cm3 converted to dm3. **How do you calculate the enthalpy change of neutralisation, and what are its units?** The enthalpy change (ΔH) is calculated using ΔH = q / n, with units in kJ/mol. **What is the known enthalpy change of neutralisation for this reaction?** The literature value is -50 kJ/mol. **Why should the experimental enthalpy change of neutralisation be negative?** The experimental ΔH is negative because neutralisation reactions typically release energy (are exothermic), resulting in a temperature increase. **How does your experimental result compare to the literature value of -57 kJ/mol?** The experimental result may differ due to factors like heat loss. A smaller observed temperature change could lead to a lower calculated ΔH value. **What improvement could be made to the method to increase accuracy?** Adding a lid to the polystyrene cup could reduce heat loss and improve the accuracy of temperature measurements.