The enthalpy change of reaction, ∆H, for the decomposition of sodium hydrogencarbonate, NaHCO3(s), cannot be measured directly. 2NaHCO3(s) → Na2CO3(s) + H2O(I) + CO2(g) A student must carry out two separate experiments and use the results of these experiments to determine the enthalpy change of reaction for the decomposition of sodium hydrogencarbonate. In both experiments the student used a weighing boat. A weighing boat is a small vessel used to contain solid samples when they are weighed. Experiment 1 Reaction between sodium carbonate, Na2CO3(s), and dilute hydrochloric acid, HCl(aq) step 1 The student added approximately 3g of Na2CO3(s) to a weighing boat and accurately measured the combined mass of the weighing boat and Na2CO3(s). This mass was recorded in Table 1.1. step 2 The student used a measuring cylinder to measure 50 cm³ of 2 moldm-3 HCl(aq). step 3 The experiment was carried out and the results were recorded in Table 1.2. step 4 The student reweighed the empty weighing boat and recorded the mass in Table 1.1. [Table 1.1 mass results from Experiment 1] [Table 1.2 temperature results from Experiment 1] Experiment 2 Reaction between sodium hydrogencarbonate, NaHCO3(s), and dilute hydrochloric acid, HCl(aq) step 1 The student weighed an empty weighing boat and recorded the mass in Table 1.3. step 2 The student added exactly 4.20g of NaHCO3(s) to the weighing boat and recorded the mass in Table 1.3. step 3 The student carried out the same experimental procedure as in steps 2 and 3 of Experiment 1. [Table 1.3 mass results from Experiment 2]