Potassium hydrogencarbonate, KHCO3, decomposes when strongly heated to form potassium carbonate, K2CO3. 2KHCO3(s) → K2CO3(s) + CO2(g) + H₂O(I) A student plans to determine the value for the enthalpy change for this reaction, ΔΗ₁, which cannot be determined directly. The student carries out two separate experiments using the following apparatus. [Figure showing polystyrene cup, thermometer, solid, 2.0 mol dm-3 hydrochloric acid] Experiment 1 uses solid KHCO3. Experiment 2 uses solid K2CO3. The following method is used for both experiments: • Transfer 50.00 cm³, an excess, of 2 mol dm⁻³ hydrochloric acid into a cup. • After 2 minutes, record the temperature of the acid. • Weigh approximately 0.0250 moles of solid. • Add the solid to the acid, stir the mixture using a thermometer and record the temperature throughout the reaction. Hazard information: 2 mol dm⁻³ hydrochloric acid is irritant, solid potassium hydrogencarbonate and solid potassium carbonate may cause irritation to the skin and eyes. The equations for the two reactions are: reaction 1 KHCO3(s) + HCl(aq) → KCl(aq) + CO2(g) + H₂O(I) reaction 2 K2CO3(s) + 2HCl(aq) → 2KCl(aq) + CO2(g) + H₂O(I)