Lab4_Thermo2

# Lab4_Thermo2 - NAME and ID Number Kevin Stock 0760631 Quiz Section BV LAB PARTNER Ben Spector EXPERIMENT 4 THERMODYNAMICS II THE TEMPERATURE

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LAB PARTNER: Ben Spector Quiz Section: BV Total Points = 60 (5 notebook, 55 template) PURPOSE AND METHOD DATA AND CALCULATIONS A. Standardization of NaOH Run 1 Run 2 Run 3** Mass of KHP 0.14 0.11 0.12 moles KHP 0.000695 0.000553 0.000573 Initial buret reading, mL 0.03 0.00 0.20 Final buret reading, mL 6.70 5.78 6.04 mL NaOH titrated 6.67 5.78 5.84 L NaOH titrated 0.01 0.01 0.01 [NaOH], moles/L 0.1042 0.0957 0.0981 Average, [NaOH] 0.0994 M 4 pts Table 1: NaOH Standardization How are the solubility products (K sp ) of KHP at various temperatures determined? ( 3 pts ) K sp = [K + (aq) ] * [HP - (aq) ] [K + (aq) ] = [HP - (aq) ], because there is one mole of K + (aq) for every mole of HP - (aq) . Therefore, we can write the equation K sp = x 2 , where x is the concentration of K + (aq) . We can calculate [K + (aq) ] by using the data gathered from the titration with NaOH. Moles NaOH = Moles K + (aq) (Liters NaOH) * [NaOH] = Moles K + (aq) [K + (aq) ] = (Moles K + (aq) ) / (Liters KHP solution) Plugging this value back into the equation for K sp gives the answer. How is K sp in a saturated solution of KHP in 0.50 M KCl determined? (3 pts ) K sp in a saturated solution of KHP in 0.50 M KCl is determined using both the titration with NaOH and flame emission analysis. As in the unsaturated solution, the concentration of HP - (aq) is determined using the (Moles NaOH) / (Liters KHP solution) However, [K + (aq) ] ≠ [HP - (aq) ] in the saturated solution because of the K + present from KCl. The intensity of the saturated solution will be compared to a graph of [K + (aq) ] versus intensity to determine the [K + (aq) ]. From there the values of [K + (aq) ] and [HP - (aq) ] can be placed into the original equation: K sp = [K + (aq) ] * [HP - (aq) ] . EXPERIMENT 4: THERMODYNAMICS II THE TEMPERATURE DEPENDENCE OF THE SOLUBILITY PRODUCT, HEAT OF SOLUTION, AND ENTROPY OF SOLUTION OF POTASSIUM HYDROGEN PHTHALATE Show the calculation for determining [NaOH] for one of the runs. May be typed or NEATLY handwritten. [NaOH], mol/L = (NaOH, mol) / (NaOH, L) KHP, mol = NaOH, mol [NaOH], mol/L = (KHP, mol) / (NaOH, L) [NaOH], mol/L = (0.000695 mol) / (0.00667 L) [NaOH], mol/L = 0.104 mol/L By signing below, you certify that you have not falsified data, that you have not plagiarized any part of this lab report, and that all calculations and responses other than the reporting of raw data are your own independent work. Failure to sign this declaration will

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## This note was uploaded on 07/07/2011 for the course CHEM 152 taught by Professor Chiu during the Spring '08 term at University of Washington.

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Lab4_Thermo2 - NAME and ID Number Kevin Stock 0760631 Quiz Section BV LAB PARTNER Ben Spector EXPERIMENT 4 THERMODYNAMICS II THE TEMPERATURE

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