SPECTROPHOTOMETRIC DETERMINATION OF A SOLUBILITY PRODUCT CONSTANT LAB 7. How Full must the cuvette be in order to obtain accurate measurements? A) What should be used as the "Blank" for setting 100% T?

= 209; S =32 ). What is the solubility of Bi2S3 in g/L (At. Mass: Bi = Ksp Bi2S3= 1.6 x 10-72 Answer format: 1.00x10-14 (Don't put the unit. Round-off your final answer in two decimal place)

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help asap Ostwald ripening (digestion) improves the purity and crystallinity of the precipitate. True False

A. Standardlzatlon of thlosulfate solutlon Trial 1 Trial 2 Trial 3 Initial volume of thiosulfate (mL) 0.00 20.05 2.3 Final volume of thiosulfate (mL) 20.05 40.05 22.15 Volume of thiosulfate used (mL) Molarity of thiosulfate Average Molarity of thiosulfate Calculate the molarity of the thiosulfate solution using the formula: 6 mmol S20,²- 1 mmol 10, Ms,0,2- 0.004167 M 10,- 20.00 ml Vol S20,²- used (mL)

Name: Date: Section: Report Sheet: Determination of Molecular Weight Through Freezing Point Depression Analysis 30 Part A: Volume of Cyclohexane mL Mass of cyclohexane (d =0.7786 g/mL) 6.0 °C Freezing Point of cyclohexane 128 Part B: Molecular Weight of Naphthalene g/mol 0.23 Mass of Sample 1 Moles of Sample 1 Mass of Sample 2 0.18 Moles of Sample 2 Moles m (mol/kg solvent) T,('C) AT, Naphthalene 5.1 TRIAL 1 5.3 TRAIL 2 k, Cyclohexane CC/m) Part C: Unknown Number 0.21 0.19 Mass of Sample 1 Mass of Sample 2 Grams Unknown T,('C) AT 0.21 4.8 TRIAL 1 0.19 5.0 TRAIL 2 Moles UnknownTRIAL 1 (moles) TRIAL 2 (moles) TRIAL 1 (g/mol)TRIAL 2 (g/mol) Molecular Weight Unknown (g/mol) AVERAGE MOLECULAR WEIGHT OF UNKNOWN

Better yield of crystal can be obtained if the alum solution is placed into refrigerator for a few days. Explain why. Solubility of alum, KAl(SO4)2•12 H2O in an aqueous solution at 0 degree Cecius is 114 g/L. In this experiment, calculate the weight of alum remain in the solution after crystallization completed. (Volume = 40 mL) p.s. please answer both questions

3. What mass of BaCl2 is needed to dissolve in 1.2 kg water to prepare 0.500m BaCl2 solution? Rubrics for Scoring

Average mass of the precipitate MgNH4PO4·6H2O (s) / g Average phosphate concentration in water sample (mass/volume %) % difference of 2 trials

If the same mass of NazSO4 (MW: 142 g/mol) and K2SO4 (MW: 174 g/mol) were weighed and used for the gravimetry experiment, which will yield a greater amount of precipitate? Assume that the experiment was done correctly. A Indeterminate, it will depend on the amount of Bacl2 used. B K„so̟ , because it has a larger molecular weight. They will yield the same amount of precipitate because the same mass was initially weighed. D Na „So, , because it has a smaller molecular weight.