Download Determining the Maximum Heat Release in the Reaction of NaClO and KI using Stoichiometry - and more Lab Reports Chemistry in PDF only on Docsity! Date Performed: 10/13/2008 Name: Justin Ruggiero Date Submitted: 10/20/2008 Partner: John Haught Instructor: Ali Nebipasagil Stoichiometry Objective The objective in this lab is to determine the stoichiometry of the reaction of NaClO and KI in an aqueous solution. Experimental Data Mole fraction of NaClO Volume KI (mL) Volume NaClO (mL) Initial temperature (°C) Final temperature (°C) ΔTT (°C) 1.0 0 50 22.79 22.79 0.00 0.90 5 45 19.93 22.79 2.86 0.80 10 40 19.95 25.60 5.65 0.70 15 35 20.19 26.13 5.94 0.60 20 30 20.26 26.27 6.01 0.50 25 25 19.92 24.05 4.13 0.40 30 20 19.96 23.36 3.40 0.30 35 15 19.57 22.06 2.49 0.20 40 10 19.62 21.29 1.67 0.10 45 5 19.46 20.02 0.56 0.00 50 0 19.46 19.46 0.00 Maximum heat release (as graphed)....………………………………………….. 0.70 Mole fraction of NaClO Sample Calculations Mole fraction NaClO (volume) = (45 mL NaClO)/(45 mL NaClO + 5 mL KI) = 0.90 Initial Temperature = ((19.90 °C * 15 mL KI)+(21.31 °C * 35 mL NaClO))/ (15 mL KI + 35mL NaClO) = 20.19°C Mole fraction NaClO (graph) = (7 mol NaClO)/(7 mol NaClO + 3 mol KI) (maximum heat release) = 0.70 Results and Conclusions In this lab, students found the maximum heat release of the reaction that occurs between NaClO and KI in an aqueous solution. Through the method of stoichiometry, students were able to yield an initial temperature of each solution and the mole fraction for all the experiments. This was seen as the amount of KI and NaClO were decreased by 5 mL and increased by 5 mL, respectively, after each trial. After all trials, it was determined that the maximum heat release occurred at .70 mole fraction of NaClO. Discussion of Experimental Uncertainty Due to the measuring apparatus available in this lab, error was virtually inevitable for every group. Students had to obtain amounts greater than 25 mL of each solution throughout the trials with a 25 mL graduated cylinder. To do this, students had to measure an amount in the instrument, and then empty into the designated beaker. After that, the students had to measure in the same graduate and get the final amount whatever was needed. When this is done, not all of the fluid is emptied and the amounts aren’t exact in the appropriate beaker. Another common error occurred in groups when a person would measure the temperature of one of the chemicals and not put the MeasureNet probe in water before obtaining the temperature of the next solution. When this happens, the chemicals become mixed and the amount of the solution collected is diluted and not completely accurate. Also, some of the reaction already takes place which would reflect a lower final temperature than actual. Answers to Definitions a. A stoichiometric coefficient is the number in front of a compound/element that represents the amount of moles that are present for it in a balanced chemical equation. b. A mole fraction is a proportional value of the amount of moles of a compound/element in a balanced chemical equation in comparison to another in the same equation. c. Molarity is the amount of moles in a solution divided by the amount of liters of the entire solution.
