SCH4U U2L2 Lab

SCH4U U2L2 Lab Purpose: This experiment aims to find out how much heat is absorbed or released when a salt dissolves in a solution, using calorimetry. Sample Mass of water Initial temp of water Final temp of water Change in temp of water Energy change Mass of salt used (g) Enthalp y of solution kJ/g Enthalp y of solution kJ/mol NaOH 75 g 21.4 C 40.4 C 19 C 5,962.2 J 6.28 g 0.94 kJ/g 37.59 kJ/mol KCl 75 g 21.3 C 16.3 C -5 C -1569 J 5.98 g 0.28 kJ/g 20.7 kJ/mol 1. Calculate the percent error for both of the salts enthalpy of solution. NaOH = ((44.2-37.59) / 44.2) x 100 = 14.95% error KCl = ((17.2 - 20.7) / 17.2) x 100 = -20.35% error 2. Suggest three sources of error in this experiment, not including human errors One source of error could be from the calorimeter. Some of the heat could have been transferred to the air or the styrofoam cup, meaning that it was not a completely enclosed space for the experiment. Another source of an error could have been that the scale exhibited variability and did not yield a precise measurement. Taking into account that the substances were only measured once before, an inaccurate quantity could lead to discrepancies in other recorded values. Lastly, the third error could have been if the calorimeter or scale was not settled down at the time of measuring, so it was not as accurate. it is usually better to wait, or take multiple measurements beforehand in order to make sure there's no errors. 3. If some heat were transferred to the air or styrofoam cup, would your calculated enthalpy of solution of the salt be too high or too low? I think the enthalpy would be too low if heat were to be transferred to the air or the styrofoam cup. This is because the calculated temperature change would be too low because of the heat