Chem 152 - Lab 4 - Thermodynamics 2

Chem 152 - Lab 4 - Thermodynamics 2 - NAME and ID Number...

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NAME and ID Number: Alice Meng-Ju Hsieh 0734371 LAB PARTNER: Chris Luong Total Points = 60 (template plus notebook pages) Notebok pages (5 pts) - Are yours organized and legible so that your TA can read them and find any information he/she might be looking for? PURPOSE AND METHOD DATA AND CALCULATIONS A. Standardization of NaOH Run 1 Run 2 Run 3** Mass of KHP 0.15 0.13 moles KHP 0.000725 0.000656 Initial buret reading, mL 0.11 0.15 Final buret reading, mL 7.45 6.85 mL NaOH titrated 7.24 6.70 L NaOH titrated 0.01 0.00670 [NaOH], moles/L 0.100 0.0979 Average, [NaOH] 0.0990 M 4 pts Quiz Section: AP Table 1: NaOH Standardization How are the solubility products (K sp ) of KHP at various temperatures determined? ( 3 pts ) The solubility products (Ksp) of KHP at various temperatures is determined by performing titrations with NaOH to determine the concentration of NaOH first. Then we can use standardized NaOH solution to titrate with various saturated KHP solutions at different temperatures. Since the mole ratio is 1:1, we know the concentration of K+ must equal the concentration of HP-. We know Ksp of KHP = [K+][HP-] and the concentration of K+ is the equal to the concentration of HP-. Also, mmoles of HP- is the same as mmoles of NaOH. How is K sp in a saturated solution of KHP in 0.50 M KCl determined? (3 pts ) Ksp in a saturated solution of KHP in 0.50M KCl is determined by first preparing five KCl standard solutions with different concentrations of [K+]. The amount of solution to add is calculated in the pre-lab. Then, we will dilute 0.50M KCl/KHP solution by a factor of 2500. To measure the intensity of each solution, we will use a flame photomter. By plotting a graph of intensity vs. the concentration of [K+] allows us to calculate the concentration of K+ ions. Because K+ and HP- are 1:1 ratio, the concentration of K+ equals the concentration HP-. Then we can find the value of Ksp because Ksp = [K+][HP-]. Also, the concentration of HP- can be determined by titrating with ~0.1M NaOH solution, which we found the concentration of NaOH during part A of the lab. EXPERIMENT 4: THERMODYNAMICS II THE TEMPERATURE DEPENDENCE OF THE SOLUBILITY PRODUCT, HEAT OF SOLUTION, AND ENTROPY OF SOLUTION OF POTASSIUM HYDROGEN PHTHALATE By signing below, you certify that you have not falsified data and that you have not plagiarized any part of this lab report.
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