Name: Quiz Section: ID Number: Lab Partner: EXPERIMENT 4: THERMODYNAMICS II Note: THE TEMPERATURE DEPENDENCE OF THE SOLUBILITY PRODUCT, HEAT OF SOLUTION, AND All sections of ENTROPY OF SOLUTION OF POTASSIUM HYDROGEN PHTHALATE this report must be typed Total Points = 60 (5 notebook, 55 template) By signing below, you certify that you have not falsified data, that you have not plagiarized any part of this lab report, an d that all calculations and responses other than the reporting of raw data are your own independent work. Failure to sign this declaration will cost you 5 points. Signature: PURPOSE AND METHOD How are the solubility products (K sp) of KHP at various temperatures determined? (3 pts) How is Ksp in a saturated solution of KHP in 0.50 M KCl determined? (3 pts) DATA AND CALCULATIONS A. Flame emission determination of [K+] in the 0.50 M KCl + KHP (sat) solution Preparation of Standards DATA Table 1: Volume of 5.00x10-3 M needed to make Table 2: Flame Photometer Data 50 mL of each standard solution (from prelab) Solution [K+], (M) Intensity Standard [K+], (M) mL of stock Standard 1 7.50E-05 1 7.50 E-5 Standard 2 1.50E-04 2 1.50 E-4 Standard 3 2.25E-04 3 2.25 E-4 Standard 4 3.00E-04 4 3.00 E-4 Standard 5 3.75E-04 5 3.75 E-4 Temperature,oC Intensity KHP(sat) in 0.50 M KCl Plot of Intensity vs [K+] (M) Add a Trendline and Trendline Eqn and on your plot and be sure to include a titles for the plot and each axis. 3 pts slope M-1 y-intercept + Table 3: Flame Emission Determination of [K ] in the original sample o [K+] in Measured + [K ] in Original Solution Temperature, C Solution (M) Dilution factor (M) Type the calculation you used to determine [K+] in the measured and original solutions above. 3 pts B. Standardization of NaOH Table 4: NaOH Standardization Run 1 Run 2 Run 3** Mass of KHP, g moles KHP Initial buret reading, mL Final buret reading, mL mL NaOH titrated L NaOH titrated [NaOH], moles/L Average, [NaOH] M Type the calculation for determining [NaOH] for one of the runs. 3 pts **If you only performed two titrations, type the calculation that you used to determine that you did not need to do a third titration. C. Titrations of KHP Samples with and without KCl mL of KHP(aq) used in titrations mL Guide for completing Table 5: Move from left to right in this table, entering your data and doing the calculations necessary for the next column. Calculations: a) convert T to Kelvin, 2) calculate mL of NaOH added, 3) calculate the mmoles (10-3 moles) of NaOH added (1:1 reaction, so moles NaOH added equal moles of HP- present), 4) molarity of HP- (from mL and moles), 5) Ksp from [HP-], and then 1/T and ln Ksp for the plot below. Let Excel help with the calculations: enter your data for temperature and buret readings, then type the necessary formulas in the first cell of each of the other columns and copy the formula to the cells below it down the column. Table 5: Titration Data and Calculations DO NOT enter the data for the solution with KCl in this table Final buret Initial buret reading mL NaOH mmoles HP- Temperature, oC Temperature, K reading Molarity HP- Ksp 1/T (in K) ln(Ksp) (mL) added (=mmoles NaOH) (mL) Type the calculations you performed for the Room Temp (~22̊ C) solution. (2pts each) mmoles NaOH: [HP-]: Ksp: Plot of ln(Ksp) vs 1/T(K) Add a Trendline and Trendline Eqn and on your plot and be sure to include a titles for the plot and each axis. 3 pts slope K R J/mol*K y-intercept DHoSoln DSoSoln Typeyour calculations for DH and DS. (2 pts each) DH = DS = Table 6: Titration of RT (no KCl) solution with NaOH(aq) to determine [HP-] mmoles* Initial buret reading Final buret mL NaOH NaOH Temperature, oC (=mmoles Molarity HP- (mL) reading (mL) titrated HP-) 0.0 0.00 0.00 0.00 0.000 0.000 autofills from Table 5 Average M mL of KHP(aq) used in titrations mL 2 pts Ksp at room temperature (no KCl) (from Table 5 and two more replicates) - Table 7: Titration of RT KHP in KCl with NaOH(aq) to determine [HP ] mmoles* Initial buret reading Final buret mL NaOH NaOH Temperature, oC (=mmoles Molarity HP- (mL) reading (mL) titrated HP-) Average M: mL of KHP(aq) in KCl used in titrations mL 2 pts Ksp in 0.50 M KCl (from Tables 3 and 7) Type the calculations for Ksp in 0.50 M KCl above and the % difference between the two Ksp values you obtained. 4 pts Ksp: % difference : KHP vs KHP/KCl, both at room temp RESULTS AND DISCUSSION 1. Using a 15% difference as acceptable, are the room temperature K sp values with and without KCl the same? 2 pts 2. Based on your results at room temperature, what is the solubility of KHP in g/L 3 pts 3. What will happen to the solubility and Ksp when NaOH(aq) is added to a satuared solution of KHP. Explain your reasoning. 4 pts 4. What will happen to the solubility and Ksp when HCl(aq) is added to a saturated solution of KHP. Explain your reasoning. 4 pts 5. Based on a previous quarter, DHoSoln = 34.1 kJ/ mole and the DSoSoln = 120 J/K·mole. 3 pts How do your results compare (calculate and comment on % difference)? 6. What is the biggest source of error in the determination of the K sp values? 2 pts Laboratory Waste Evaluation (1 pt) Laboratory waste is considered anything generated during an experiment that is disposed of down the sewer drain, thrown in the garbage, collected in a container for disposal by the UW Environmental Health & Safety department, or released into the environment. Based on the written lab procedure and your actions during the lab, list the identity and approximate amount (mass or volume) of waste that you generated while performing this experiment.
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