Enthalpy Formal Lab Report PDF

Preview

Summary

Enthalpy and Hess's Law formal lab report...

Description

Enthalpy of Formation and Hess’ Law Lab Report By Zachary James Chemistry 1411 Section 2009 Experiment 7 3-28-2019

Executive Summary Throughout this report, the introduction will explain the beginning premise of the enthalpy lab experiment. The experimental setup segment will list all the material throughout both of the experiments. The procedure will then explain the process of the experiments. Then, results will annotate and describe the important data collected. Finally, the conclusion will summarize the report and wrap it up. Introduction The experiment is produced to determine the enthalpy of change between an unknown salt product and reactants such as Nitric Acid and Ammonia Hydroxide. In the beginning of the experiment, you must find the salt in Experiment 1 to be able to use that salt in Experiment 2. For our experiment, the unknown salt is Ammonia Hydroxide and is mixed with water to determine the enthalpy change. Experimental Setup The experiment was split into two separate parts. Experiment 1 required 50 ml of 2.05 M Ammonia Hydroxide in a 50 ml beaker and 50 ml of 2.0 M Nitric Acid in a Styrofoam cup to act as a calorimeter. The calorimeter was assembled using the Styrofoam cup, a stirring bar, an iron ring and a small cardboard square to prevent the Styrofoam cup from tipping over and spilling its contents. The Vernier interface was used to collect the data from the changes in temperature. We used two different thermistors to record the temperature to detect the exact and minute changes in the enthalpy change. In Experiment 2, we required 100 ml of water in the Styrofoam cup and 7.4612 grams of 1.0 M Ammonia Hydroxide on a weighing paper. The

setup for experiment 2 was almost identical to that from experiment 1. The calorimeter was to be recreated in the same manner as experiment 1 except apart from only one thermistor. Procedure To begin Experiment 1, the calorimeter was assembled by taking the Styrofoam cup and placing it on the heating and stirring plate. We then added a stirring bar to the cup along with the 50 ml of Hydrochloric Acid and turned on the stirring bar. The iron ring was then placed on top of the cup to prevent tipping and a cardboard square piece was placed on top to prevent the spilling of the Hydrochloric Acid. The thermistors were then inserted into the interface and then plugged into the computer to calculate the exact temperatures of the liquids. Thermistor 1 was placed into the calorimeter through a small hold in the cardboard cover. Thermistor 2 was placed into the beaker of Ammonia Hydroxide. We let the thermistors settle out to continue to read an accurate temperature reading before starting the procedure. The data was then collected before the Ammonia Hydroxide was added into the calorimeter containing the Hydrochloric Acid. A balanced equation was produced from this procedure. From this balanced equation and procedure, the limiting reactant Hydrochloric Acid was determined, and the grams of the salt Ammonia Hydroxide was produced and calculated by using the moles of Ammonia Hydroxide produced multiplied by its molar mass. This was the mass that we needed to calculate in order to do experiment 2. Experiment 2 required the same setup of the calorimeter as in Experiment 1. Except, we used 100 ml of water to be placed in the Styrofoam cup and the interface only required one of the thermistors to be plugged into Channel 1 in the interface. The 7.4612 grams of Ammonia Hydroxide calculated from Experiment 2 was obtained. The thermistor was placed back into the Styrofoam cup through the small hole in the cardboard. We let the thermistor

settle out to continue to read an accurate temperature reading before starting the procedure. The data was then collected and then after 10 seconds the Ammonia Hydroxide solid was placed into the calorimeter. There was a sharp decrease in temperature for about 16 seconds and then the final temperature was calculated. Results See Table 1: Minimum Temperature: 21.92 degrees Celsius Maximum Temperature: 27.00 degrees Celsius Change in Temperature: 5.08 degrees Celsius 10 seconds of data collection was allowed to secure an initial temperature of 21.92 for the solution inside the calorimeter. At 10 seconds, the 50 ml of 2.05 M Ammonia Hydroxide was poured into the calorimeter. After 18 seconds, a final temperature of 27.00 was recorded. See Table 2: Minimum Temperature: 23.59 degrees Celsius Maximum Temperature: 27.47 degrees Celsius Change in Temperature: 3.88 degrees Celsius About 10 seconds of data collection was allowed to secure an initial temperature of 21.10 for the calorimeter. The 7.4612 grams of solid Ammonia Hydroxide was then added to the solution

inside the calorimeter. Over the course of 15 seconds the temperature began to decrease to 23.59. Human Error The large “peak” in the line of the graph was a result of human error in during the experiment. Half of the solid Ammonia Hydroxide was placed into the calorimeter before there was difficulty in placing the rest due to a small opening created by the thermistor restricting the movement of the cardboard cover which increased the time in which the temperature decreased. However, it is not a serious concern as it does not affect the final calculations as time is not an important variable needed. Conclusion This experiment was broken into two different segments but Experiment 2 was dependent on Experiment 1. Even over a small error, the important calculations from Experiment 2 was still calculated. Although the experiments were not difficult, they give way for more difficult math....