Stoichiometry Experiment: Determining the NaClO to KI Ratio in a Reaction - Prof. Patricia, Lab Reports of Chemistry

Download Stoichiometry Experiment: Determining the NaClO to KI Ratio in a Reaction - Prof. Patricia and more Lab Reports Chemistry in PDF only on Docsity! Date Performed: 10/16/08 Name: Matthew Metzger Date Submitted: 10/23/08 Partner: Getnat Ejigu Instructor: Jing Wang Stoichiometry Objective To determine the stoichiometry of the reaction between sodium hypochlorite (NaClO) and potassium iodide (KI) in aqueous solution. Experimental Data Volume of NaClO (mL) Volume of KI (mL) Temperature of NaClO (ºC) Temperature of KI (ºC) Final Temperature after mixing (ºC) 45.0 5.00 21.86 21.61 22.53 40.0 10.0 21.86 21.61 22.58 35.0 15.0 21.86 21.61 24.86 30.0 20.0 21.86 21.61 26.62 25.0 25.0 21.86 21.61 27.45 20.0 30.0 21.86 21.61 26.21 15.0 35.0 21.86 21.61 25.00 10.0 40.0 21.86 21.61 23.82 5.00 45.0 21.86 21.61 23.09 *In the experiment we ran out of sodium hypochlorite (NaClO) so we could not run the final test. Sample Calculations Initial temperature in first run: (21.86 °C x 45.0mL )+ (21.61° C x5.00mL ) 45.0mL+5.0mL =21.84 ° C Temperature change in first run: 22.53 °C – 21.84 °C = 0.69 °C Mole fraction of NaClO in the first run: 45.0mLNaClO 45.0ml NaClO+5.0mLKI =.9mol NaClO Mole fraction of KI in the first run: 5.00mLNaClO 45.0ml NaClO+5.00mLKI =.1mol KI Mole ratio: a(mole fraction of NaClO ) b(mol e fraction of KI ) = .9 .1 9:1 Results and Conclusions Volume of NaClO (mL) Volume of KI (mL) Mole Fraction of NaClO Initial Temperature (°C) Final Temperature (°C) ΔT (°C)T (°C) 45.0 5.00 .9 21.84 22.53 0.69 40.0 10.0 .8 21.81 23.58 1.77 35.0 15.0 .7 21.79 24.86 3.07 30.0 20.0 .6 21.76 26.62 4.86 25.0 25.0 .5 21.74 27.45 5.71 20.0 30.0 .4 21.71 26.21 4.50 15.0 35.0 .3 21.69 25.00 3.31 10.0 40.0 .2 21.66 23.82 2.16 5.00 45.0 .1 21.64 23.09 1.45 Discussion of Experimental Uncertainty Some areas of uncertainty in the problem are: not entirely rinsing the temperature probe or the graduated cylinders, heat loss in the polystyrene cup, and improperly reading measurements on the graduated cylinders. Another area for uncertainty is that when bleach is exposed to light it can break apart into salt and oxygen and when KI is exposed to oxygen it can form iodide Answers to Definitions Stoichiometric Coefficient: a numerical multipier of all the atoms in the formula that follows it. Mole Fraction: the concentration term expressed as the ration of the moles of one component of a mixture to the total moles present. Molarity: the moles of solute dissolved in one liter of solution.