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The percent error is 7.83% between the expected (theoretical) and experimental values that were calculated. The expected, theoretical, result would be a 0% difference between the values for (∆H_(1 )+〖∆H〗_2)and ∆H_3. In other words, ∆H_(1 )+〖∆H〗_2 should have been equal to ∆H_3. Possible reasons for error were either inherent in the lab procedure, the apparatus used or were due to human error. The only variable that is changing is the temperature meaning that the temperature and the heat of reaction have a positive correlation. If the temperature increases then the value for the enthalpy change will increase, and vice versa.
All measurements, observations and calculations were carefully checked and are therefore not a source of error. One source of error could be that the calorimeter (Styrofoam cup) was uncapped and not a perfect insulator for keeping the heat from escaping. As it was uncapped some of the heat would have been lost to the air and as one of our assumptions was that the heat released by the reactions was used only to heat the water the value calculated will be off. The consequence of this source of error would be the measurement of a lesser final temperature and therefore the heat of reaction calculated would also be less. Another source of error could be due to the use of a white Styrofoam cup and the dissolving of white sodium hydroxide pellets. It would be easy to miss if the reaction had yet to fully take place meaning the final temperature recorded would be lower and heat of reaction calculated would be lower. A final possible source of error could be that not a precisely even amount of HCl and NaOH were used for the neutralization reactions in part two and three. This could be because some was left in the graduated cylinder or the pellets, from part three, could not be measured out precisely enough. If the neutralization was incomplete the experimental value for heat of...