A student completed an experiment to determine the enthalpy of neutralisation for the reaction between ethanedioic acid solution (HOOCCOOH\text{HOOCCOOH}HOOCCOOH) and sodium hydroxide solution.
The student added 40 cm340\text{ cm}^340 cm3 of 0.40 mol dm−30.40\text{ mol dm}^{-3}0.40 mol dm−3 ethanedioic acid solution to 60 cm360\text{ cm}^360 cm3 of 0.60 mol dm−30.60\text{ mol dm}^{-3}0.60 mol dm−3 sodium hydroxide solution. The temperature increased by 3.2 ∘C3.2\ ^\circ\text{C}3.2 ∘C.
Give an equation for the reaction between ethanedioic acid solution and sodium hydroxide solution.
Calculate the enthalpy change (ΔH\Delta HΔH) per mole of water formed in this reaction. Assume that the specific heat capacity of the reaction mixture is 4.18 J K−1 g−14.18\text{ J K}^{-1}\text{ g}^{-1}4.18 J K−1 g−1 and that the density of the reaction mixture is 1.00 g cm−31.00\text{ g cm}^{-3}1.00 g cm−3.
In a similar experiment, the enthalpy of neutralisation for the reaction between nitric acid and sodium hydroxide solution was found to be −57.3 kJ mol−1-57.3\text{ kJ mol}^{-1}−57.3 kJ mol−1 per mole of water formed. Suggest an explanation for the difference between this value and your calculated value.
