Download Stoichiometry of Sodium Hypochlorite and Potassium Iodide Reaction: Temperature Change - P and more Lab Reports Chemistry in PDF only on Docsity! Date Performed: 10/16/09 Name: Rachael Harris Date Submitted: 10/23/09 Partner: Halie Sklanka Stoichiometry; Method of Continuous Variations Objective To determine the stoichiometry of the reaction between sodium hypochlorite (NaClO) and potassium iodide (KI) in aqueous solution. Experimental Data Vol. of NaClO (mL) Vol. of KI (mL) Initial temp. Of NaClO (°C) Initial Temp. Of KI (°C) Final Temp. (°C) 45.0 5.00 21.62 22.04 24.40 40.0 10.0 22.22 22.12 26.94 35.0 15.0 23.14 22.37 26.73 30.0 20.0 22.88 22.15 26.60 25.0 25.0 22.52 21.87 26.25 20.0 30.0 21.56 21.51 26.12 15.0 35.0 22.14 21.82 25.99 10.0 40.0 21.93 21.73 24.01 5.00 45.0 22.02 21.81 23.00 Sample Calculations Mole fraction NaClO = Number of NaClO moles or Vol. NaClO Number of NaClO moles + Number of KI moles Vol. NaClO + Vol. KI - Mole fraction NaClO = 45.0 mL = 0.900 mol 45.0 mL + 5.00 mL Average initial T = T1V1+T2V2 V1+V2 -Average initial T = (21.62°C)(45.0mL) + (22.04°C)(5.00mL) = 21.7°C 50.0mL ΔTT = TFinal - TInitial - ΔTT = 24.40°C – 21.66°C = 2.74°C Mole fraction of NaClO = 0.45 Mole fraction of KI= 1-mole fraction of NaClO - (1-0.40) = 0.60 - A/B ➝ 0.40 (mole fraction of NaClO) = 0.67 0.60(mole fraction of KI) -A/B = 1 moles of NaClO 1 mol KI Results and Conclusions For this lab, the greatest amount of heat that was liberated (the largest temperature change) was measured between the reaction of sodium hypochlorite (NaClO) and potassium iodide (KI). My lab partner and I measured the initial temperature of NaClO and KI, as well as their final temperature when they were reacted. Using stoichiometry, we were able to calculate the mole fraction for each trial. For each trial, the NaClO was decreased by 5.0 mL and the volume of KI was increased by 5.0 mL. At the conclusion of the trials, it was found that the maximum change of temperature, or release of heat, occurred at 0.6 mole fraction of NaClO. The coefficient for NaClO in the final equation is 1 and the coefficient for KI is 1. The final equation for the reaction between NaClO and KI is NaClO +KI ➝products + heat. The chart below depicts the various results of the trials of the lab after everything was calculated. Volume of NaClO (mL) Volume of KI (mL) Mole Fraction of NaClO Average initial T (°C) Final Temp. (°C) ΔTT (°C) 45.0 5.00 0.900 21.66 24.40 2.74 40.0 10.0 0.800 22.20 26.94 4.74 35.0 15.0 0.700 22.91 26.73 3.82 30.0 20.0 0.600 22.59 26.60 4.01 25.0 25.0 0.500 22.20 26.25 4.05 20.0 30.0 0.400 21.53 26.12 4.59 15.0 35.0 0.300 21.92 25.99 4.07 10.0 40.0 0.200 21.77 24.01 2.24 5.00 45.0 0.100 21.83 23.00 1.17 Discussion of Uncertainty The most obvious source of experimental uncertainty is not being able to get all of the solution out of the container and into the measuring apparatus. Not having the exact amounts of solution in the containers could have affected the results, resulting in error. Another area of experimental error is due to the fact that my lab partner did not take the
