Chemlab Error Analysis

5. Discussion and Error Analysis:

a). The rise in temperature was more dramatic for reaction 2 than it was for reaction 3. In reaction 1, the temperature quickly rose to 35.8 ºC in about 30 seconds whereas in reaction 2, it only rose to 26.5 ºC. In another 30 seconds, the temperature for reaction 1 increase even more to 40.9 ºC while the temperature for reaction 2 only increased up to 26.7 ºC. This indicates that more heat was generated at a faster rate for reaction 1 than for reaction 2. In addition, the temperature decreased at a faster rate for reaction 1 than for reaction 2. This may show that there was more heat loss outside the calorimeter for reaction 1 compared to reaction 2, which a third Styrofoam cup may have prevented.

b). In determining the accuracy of this experiment, the digital thermometer used to measure the temperatures is the most important. If the temperature was no measured correctly, this would cause wrong values for q or heat. This would then lead to incorrect values for the molar enthalpy change and ultimately to an incorrect value for the enthalpy of the formation of MgO. Because the accuracy for a digital thermometer is ± 0.1 ºC, the calculated enthalpy should go until the tenths place.

c). This experiment assumes that no heat is loss to the Styrofoam cups that were used as the calorimeter and also assumes that there is a constant pressure determined by the atmosphere. Heat loss to the Styrofoam cups would cause temperature measurement errors and during the course of the experiment, the room pressure may have changed between the two reactions.