ecause energy is lost by the system (199). As seen in Table 3, all but one of the results gleaned from the experiment were negative. Therefore, the general trend of the results indicate that these two precipitation reactions released heat into their surroundings. The experiment itself further reinforced our interpretation of the results. The calorimeter became warmer as the reaction progressed. Changes in which the system gives off thermal energythat is, changes that heat their surroundingsare called exothermic (Umland and Bellama 194). Thus, according to our experiments, reactions involving these two precipitation reactions we chose are exothermic processes. The reactions caused an increase in temperature by releasing heat from the system.A discrepant event occurred in the first trial of barium chloride and sodium sulfate. The heat of reaction calculation was a positive 1.37 kJ/mol. None of the other calculations gave a positive number, and our team redid the calculation for the ∆H of the first trial of barium chloride and sodium sulfate again. The result was still positive. A possible cause for this discrepancy is that an error could have been made in the temperature reading during the actual experiment.A general weakness of this experiment is that, again, our team assumed that the density and specific heat of the solutions were the same as pure water. Also, the initial temperature of the second solution was not factored into our equations. There should not have been much difference, as both solutions should have been at room temperature. However, due to these assumptions, our calculations of ∆H for the precipitation reactions are slightly inaccurate. Acid and Base Reactions:Our final experiments involved acid base reactions. The results of the acid base reactions can be found in Tables 4 and 5. For our experiments, our team chose to use acetic acid and ammonium hydroxide for our weak acid and base....
