4. Which step in up/downstream processing consists of purification and buffer exchange?

Which of the following is a good description of a standard solution as a titrant? a) selectively reactive with the analyte b) only reacts with the matrix c) oxidize when exposed to air d) reacts very slowly but completely

(a) Find the pH of a 1.00 L solution prepared with 12.43 g of base (CH2OH)3CNH2 (MW =121.135 g/mol) plus 4.67 g of its conjugate acid (CH2OH)3CNH3Cl (MW = 157.596 g/mol).(b) How many mL of 0.500 M NaOH should be added to 10.0 g of (CH2OH)3CNH3Cl to give a pH of 7.60in a final volume of 250 mLConsider the pKa of (CH2OH)3CNH3+ = 8.072

What is the easiest process to get to the result?

1. You will use 0.5mM PNPP, 0.2M Tris-HCl, and 1mM P; stock solutions to prepare two sets of five samples (Sets A and B), each with varying P; concentrations. The PNPP concentration for all samples in Set A will be 0.05mM; and 0.150mM for all samples in Set B. Fill out the tables below and use them to prepare your samples. Be aware of the following: • Prepare the samples directly in cuvettes. Prepare one sample at a time to minimize exposing PNPP to air. You can prepare the next sample while the current one is being measured. • Each sample before adding enzyme (i.e., the cuvette only contains PNPP, Pi, and Tris-HCI) is its own blank. In other words, you add the appropriate amounts of PNPP, Pi, and Tris- HCI to a cuvette, press "Measure Blank", then add 100μL of AP to the same cuvette, mix, and press "Measure Sample". • You must blank the instrument (before adding the enzyme) each time you prepare a new sample. Table 1. Sample Set A (PNPP concentration = 0.05mM) Final [Pi] (μM) Vol of…

20 ml of a 100 mg/l phenol solution in water is placed in a vial with 20 ml of a fluorocarbon solvent. The organic phase (fluorocarbon solvent) is immiscible with water. The vial is completely filled with the two phases, thus there is no air or contaminant volatilization. After an hour of agitation, the two phase system reaches equilibrium. The two phases are separated and the fluorocarbon is analyzed for total phenol. The resulting phenol concentration in the organic phase is 16.0 mg/l. Compute the unitless partition coefficient (KF-W) for phenol. Compare your calculation with KF-W obtained from an empirical relationship: log10KF-W 0.71 - 0.862log10 CWsat. KF-W means the partition between the fluorocarbon solvent, F, and water, W. Only typed solution.

A student carries out a titration to determine the molar mass and structure of a weak acid A. The student follows the method below. Dissolve a weighed mass of A in 100 cm3 of distilled water and make the solution up to 250 cm in a beaker. Add the solution of A to a burette. Titrate the solution of A with a standard solution of sodium hydroxide, NAOH. (a) What is meant by the term standard solution? (b) Sodium hydroxide is an alkali. What is meant by the term alkali? (c) The student carries out a trial, followed by three further titrations. The diagram shows the initial and final burette readings for the three further titrations. The student measures all burette readings to the nearest 0.05 cm3. Titration 1 Titration 2 Titration 3 Initial reading Final reading Initial reading Final reading Initial reading Final reading 27

Formulate a hypothesis regarding the solubility of aspirin at different pH.The experimentA) Three teaspoons of water (approx. 15 ml) were added to one tablet said to contain 300 mg of aspirin. Fizzingwas observed. Most of the tablet dissolved, but there were some solid particles. By heating the mug in amicrowave for 10 second increments until the water came to the boil (approx. 3x), all of the solid particlesdissolved. The solution was left to cool to room temperature and then placed in a fridge and NOTHINGHAPPENED. Try this yourself if you can spare two aspirin tablets, your results might look different.• Questions to ask:1. What might the fizzing bubbles be?2. Can you give a chemical explanation?3. Can you write a chemical reaction equation with aspirin reacting with something to give a gas and aspirinin another form?4. What might be the formulation (what the manufacturer mixes with aspirin in making the tablet) “trick”for aspirin to improve solubility?5. How does this compare with…

Review the list of common titration errors. Determine whether each error would cause the calculation for moles of analyte to be too high, too low, or have no effect. adding titrant past the color change of the analyte solution recording the molarity of titrant as 0.1 M rather than its actual value of 0.01 M spilling some analyte out of the flask during the titration starting the titration with air bubbles in the buret filling the buret above the 0.0 mL volume mark Answer Bank no effect too low too high 7

pure water MISSED THIS? Read Section 18.5 (Pages 817 - 822) . Express your answer in moles per liter to three significant figures. • View Available Hint(s) Calculate the molar solubility of CuX (for which = 1.27 x 10-36) in each of the following. Ksp = ? S = M Submit Part B 0.25 M CuCl2 Express your answer in moles per liter to two significant figures. • View Available Hint(s) ? S = M Submit Part C 0.23 M Na2X Express your answer in moles per liter to two significant figures. • View Available Hint(s) ΑΣφ ? S = M