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

By reference to the reacting ratio of HCl and NaOH, deduce the number of moles of NaOH required to reach equivalence.

Distinguish the terms end point and equivalence point.

(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

Molarity of Na2S2O3 (stock solution).    0.100 M Volume of diluted bleach titrated (taken from the volumetric flask).  10ml Initial Burette Reading.  14.80 Final Burette Reading     25.60 Volume of Na2S2O3 used in the titration (mL).    10.80 Moles of Na2S2O3 used in the titration.   1.71 Moles of S2O3–2 used.     1.66 Moles of I2 initially present in titration mixture 0.83 Moles of NaOCl in the diluted bleach titrated.   0.415 Moles of OCl– in the diluted bleach titrated.   ?

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.

Part A: Standardization of a Sodium Hydroxide Solution   Titration 1 Titration 2 Titration 3 Mass of 125 mL flask 45.849g 46.715g 44.953g Mass of flask and KHP 46.849g 47.745g 46.003g Initial buret reading (mL) 0.5 ml 0.5 ml 0.5 ml Final buret reading (mL) 27.8 ml 26.5 ml 26.7 ml Volume of NaOH used (mL) 45.11 ml 45.06 ml 45.14 ml   Calculations   Titration 1 Titration 2 Titration 3 Moles of KHP       Moles of NaOH       Molarity of NaOH         Average Molarity of NaOH: _______________

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