Required practical 2: measure an enthalpy change.

In the subtopic A-level required practical activities, this AQA A-Level Chemistry 7405 learning objective focuses on required practical 2: measure an enthalpy change. It belongs to A-level practical endorsement and required practical activities, so revision should stay anchored to this exact subtopic rather than drifting into a generic GCSE-level chemistry summary. Approved keywords to use include enthalpy, required practical. Calorimetry. means a technique used to measure the amount of heat involved in a chemical reaction or other processes Avoid the mistake of students often confuse the enthalpy change with the total heat released or absorbed during a reaction, neglecting to consider the specific heat capacity of the solution used; instead, to correctly measure the enthalpy change, use the formula q = mcΔT, where q is the heat energy, m is the mass of the solution, c is the specific heat capacity, and ΔT is the change in temperature. For example, if 100 g of water (c = 4.18 J/g°C) is heated from 20°C to 25°C, substitute into the formula: q = 100 g × 4.18 J/g°C × (25°C - 20°C) = 2090 J. Therefore, the enthalpy change is 2090 J For exam answers, when measuring enthalpy changes, ensure to use a calorimeter to accurately record temperature changes during the reaction