16.At the midpoint of a titration curve for valine A. The concentration of a conjugate base is equal to the concentration of a conjugate B. The pH equals the pKa C. The ability of the solution to buffer is best D. All of the above E. A and B only 17. The ratio of the concentration of a forms of a weak acid necessary to satisfy the Henderson-Hasselbalch equation. A. Conjugate acid; conjugate base B. Conjugate base; conjugate acid C. Proton donor; proton acceptor D. Proton acceptor; proton donor F B and D over describes the proportions of

16.At the midpoint of a titration curve for valine A. The concentration of a conjugate base is equal to the concentration of a conjugate B. The pH equals the pKa C. The ability of the solution to buffer is best D. All of the above E. A and B only 17. The ratio of the concentration of a forms of a weak acid necessary to satisfy the Henderson-Hasselbalch equation. A. Conjugate acid; conjugate base B. Conjugate base; conjugate acid C. Proton donor; proton acceptor D. Proton acceptor; proton donor F B and D over describes the proportions of

Chemical Principles in the Laboratory

11th Edition

ISBN:9781305264434

Author:Emil Slowinski, Wayne C. Wolsey, Robert Rossi

Publisher:Emil Slowinski, Wayne C. Wolsey, Robert Rossi

Chapter43: Analysis For Vitamin C

Section: Chapter Questions

Problem 2ASA

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Based on the table below: 1). create a titration curve of pH vs. volume NaOH (graph in in Excel). Indicate on graph the location of each pKa (pka1, pKa2, pKaR) , first and second equivalence point and pI. Show all your calculations. 2). 1st derivative plot of ΔpH / Δvol NaOH an the y-axis and average vol NaOH on the x-axis (graph in Excel). Highlight (label) the equivalence points Table 1.2 - Titration of an unknown amino acid with NaOH Vol. NaOH (mL) pH Avg.Vol. NaOH (mL) pH / Vol NaOH 0.00 2.12 0.5 0.02 1.00 2.14 1.5 -0.02 2.00 2.12 2.5 0.13 3.00 2.25 3.5 0.07 4.00 2.32 4.5 0.06 5.00 2.38 5.5 0.06 6.00 2.44 6.5 0.07 7.00 2.51 7.5 0.1 8.00 2.61 8.5 0.11 9.00 2.72 9.5 0.08 10.00 2.80 10.5 0.29 11.00 3.09 11.5 0.44 12.00 3.53 12.5 1.17 13.00 4.70 13.5 0.51 14.00 5.21 14.5 0.29 15.00 5.50 15.5 0.18 16.00 5.68…
Please sketch the titration curve of lysine. Then annotate X-axis, Y-axis, each pKa, PI and ionizable forms of lysine on the curve. Note: the value of pKa or PI is not required.
The initial pH of a 0.2M arginine solution is 14. a. What is the predominant structure of arginine in solution at this pH? b. Draw the titration curve that would result if this solution were titrated with 1M HCl to pH 7.
1) You are asked to prepare a buffer for a protein assay. This protein works best at a slightly acidic pH of 5.5. a. From the list of Acids and conjugate bases which pair would you pick. (The list is in the attached image) b. You are asked to make a 1M stock solu on of the Buffer, how many grams of each acid and base would you need to make a 500mL stock. c. For the experiment, the final concentra on of the buffer should be 50mM. How many mL of your stock would you need to make 2L. Hint: M1V1=M2V2
You are preparing a sample for Kjeldahl analysis. Based on the protein information in the sample, you need to use a buffer with pH=8. Which of the following weak base and its conjugate acid will you use? a. NH2OH, pKb = 8.04b. CH3CH2NH2, pKb = 3.37c. NaH2PO4, pKa = 7.21
A solution of amino acid having carboxylic side chain was titrated against NaOH. If initial pH of the solution was 2.8. Describe the state of the functional groups of the amino acid at the initial pH and at 10.5.
You are given 0.5 M solution of the amino acid Arginine. pK1 (α-carboxyl group) = 2.17 pK2 (α- amino group) = 9.03 and pK3 (guanidine group) = 12.48 Answer the following questions. a. Determine the pH of the solution if you add 15 mL 0.25 M HCl to 10 mL of the 0.5 M Arginine. Assume that Arginine is in isotonic state. Show all calculations. Draw the structure of the amino acid at the pH determined in question 1a.
Region/point where AA is predominantly present as a (-1) charged species? The effective buffering range for the amino acid in the acidic region? Region/point where the solution has 50:50 percent mixture of the (0) and (-1) species
Does the titrated amino acids appear to be acidic, basic, or neutral amino acids? Please explain your conclusion with reference to the data and to theory.
If to 100 ml of a solution of CH3COOH with a concentration of 0.0928 N. a) 200 ml of distilled water was added. Determine its new concentration expressed to 4 decimal places, and determine the pH of the final solution. Data: pKa = 4.756 at 25°C. Consider that degree of dissociation is very small. b) If it is mixed with 100 ml of a 0.0989 N CH3COONa solution. What is the pH of the buffer solution.
Sketch the titration curve of CRIP and draw the corresponding predominant structue at each equivalence point. Determine: 1) PI 2) Charge of the peptide above at pH 10 3) Charge of the peptide above at pH 24) Charge of the peptide above at around 12.5?
You are conducting a biochemical experiment with an enzyme that has optimal activity at pH = 10.50. You decide to use carbonate (pKa1 = 6.38, pKa2 = 10.30) as the buffer to keep the pH stable throughout the enzymatic reaction. (Recall that the formula for carbonic acid is H2CO3.) You prepare a 0.6 M solution of carbonate buffer at pH = 10.50. Calculate the concentrations of the major carbonate species in your solution. Show your calculations.