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Thermo II postlab

# Thermo II postlab - Name ID Number Emily Tsiao 930609 Quiz...

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Name: Emily Tsiao Quiz Section: AD ID Number: 930609 Lab Partner: Haley Smith Total Points = 60 (5 notebook, 55 template) PURPOSE AND METHOD DATA AND CALCULATIONS A. Flame emission determination of [K+] in the 0.50 M KCl + KHP (sat) solution Preparation of Standards DATA 50 mL of each standard solution (from prelab) Solution Intensity Standard [K+], (M) mL of stock Standard 1 7.50E-05 84 1 7.50 E-5 0.75 Standard 2 1.50E-04 152 2 1.50 E-4 1.50 Standard 3 2.25E-04 222 3 2.25 E-4 2.25 Standard 4 3.00E-04 318 4 3.00 E-4 3.00 Standard 5 3.75E-04 373 5 3.75 E-4 3.75 Intensity 3 pts slope y-intercept Table 1 : Volume of 5.00x10 -3 M needed to make Table 2 : Flame Photometer Data [K + ], (M) Temperature, o C KHP(sat) in 0.50 M KCl M -1 How are the solubility products (K sp ) of KHP at various temperatures determined? ( 3 pts ) In order to calculate the K sp of KHP at various temperatures, we titrate saturated KHP solutions at various temperatures with a standardized NaOH solution. Using data from these titrations, we can calculate the moles of NaOH added at equilibrium, which is equal to the moles of KHP in the solution. then, using the amount of KHP in the original solution, we can determine the molarity of HP - in each of the solutions. Because each solution is saturated and KHP dissociates in a 1:1 ratio, we know that [HP - ] is equal to [K + ], thus we can calculate K sp using the equation: K sp =[HP - ][K + ]. How is K sp in a saturated solution of KHP in 0.50 M KCl determined? (3 pts ) In order to calculate K sp of a saturated KHP solution in the presence of a common ion (from 0.50 M KCl), we calculate [K + ] and [HP - ] individually. The [HP - ] is found by titrating the KHP/KCl mixture with the standardized NaOH solution in the same way as Part B. To calculate [K + ], though, we compare the intensity of a diluted KHP/KCl solution (using a flame photometer) to a group of standard solutions.

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