Calculate the pH of a buffer that is 0.225 M HC₂H₃O₂ and 0.162 M KC₂H₃O₂. The K_a for HC₂H₃O₂ is 1.8

How do serine proteases hydrolyze dietary proteins? Describe the catalytic activity of chymotrypsin.

111 nmol of an antibody that binds strongly to the antigen protein G is covalently bound to the support of an affinity column with a void volume of 1.54 mL. The association equilibrium constant (K_A) for the binding of protein G to the antibody is 6.67 × 10⁸ M^–1 at pH 7.1. Calculate the retention factor for protein G on this column at pH 7.1.

k = ___

At pH 7.1 and a flow rate of 2.00 mL/min, how many minutes would it take protein G to elute from this column?

t_{r = ____} min

If a pH 3.2 elution buffer is applied to the column, protein G elutes at 3.48 min using a flow rate of 2.00 mL/min. Under these conditions, what is the association equilibrium constant between protein G and the antibody?

K_A = ____ M^-1

As we’ve seen before in this class, the roasting of limestone (calcium carbonate) to make quicklime (calcium oxide) and carbon dioxide is an important industrial process because the quicklime is used to make cement, among other things. How many kJ of heat are needed to produce 1.0 metric tons of quicklime?

Methanol, CH₃OH, is a nonelectrolyte; ammonia, NH₃, is a weak electrolyte; and calcium hydroxide, Ca(OH)₂, is a strong electrolyte. What are the solute particles present in aqueous solutions of each compound? (Select all that apply.)

If 0.1 mol of each compound is dissolved in solution, which one contains about 0.3 mol of solute particles, which contains 0.1 mol of solute particles, and which contains somewhere between 0.1 and 0.2 mol of solute particles?

. What are the main characteristics of the mobile and stationary phases in gas

chromatography?

(10)

2. What are the main applications and advantages of temperature programming in GC? What

is the equivalent procedure in HPLC?

(20)

3. What is the purpose of derivatization in HPLC?

(10)

4. The following retention were measured in a column of 1.10 m:

air : 18.0 s.

methyl acetate: 1.98 min.

methyl propionate: 2.24 min

methyl n-butyrate: 7.93 min.

The base width of the three peaks were of 0.19, 0.23 and 0.79 min, respectively.

Calculate a) the number of theoretical plates in the column N

b) the equivalent height of a plate H

c) the length the column should have to obtain a resolution (Rs) of 1.5

for the acetate and the propionate

(20)

5.

Name two general methods for improving the resolution of two substances on a

chromatographic column.

(10)

6.

The distribution constant for compound X between n–hexane and water is 9.6. Calculate

the concentration of X remaining in the aqueous phase after an aliquot of 50.0 mL of

0.150 M of X has been treated by extraction with the following quantities of n-hexane:

(a)

One 40.0-mL portion;

(b)

Two 20.0-mL portions;

(c)

Four 10.0-mL portions;

(d)

Eight 5.0-mL portions.

What conclusion can you make from these calculations?

(20)

7.

Describe the principle of separation in a column used for size – exclusion

chromatography. What is the separation range in term of molecular weight? Give the

definition of “gel filtration: and “gel permeation

What is the solution to the problem of the abuse of pain medications? Use references to defend response.

(a) Potassium iodate solution was prepared by dissolving 1.022 g of KIO3 (FM 214.00) in a 500 mL volumetric flask. Then 50.00 mL of the solution was pipetted into a flask and treated with excess KI (2 g) and acid (10 mL of 0.5 M H2SO4). How many millimoles of I3− are created by the reaction

b) The triiodide from part (a) reacted with 37.57 mL of Na2S2O3 solution. What is the concentration of the Na2S2O3 solution?

(c) A 1.223 g sample of solid containing ascorbic acid and inert ingredients was dissolved in dilute H2SO4 and treated with 2 g of KI and 50.00 mL of KIO3 solution from part (a). Excess triiodide required 14.30 mL of Na2S2O3 solution from part (b). Find the weight percent of ascorbic acid (FM 176.13) in the unknown.
HINT: Think "back-titration

1. Draw a structural formula for a compound that is made of carbon and hydrogen.

2. What is the difference between:

     a. an ionic bond and a covalent bond

     b. a polar bond and a nonpolar bond

A solution is made by mixing 35.0 mL of ethanol, C2H6O, and 65.0 mL of water. Assuming ideal behavior, what is the vapor pressure of the solution at 20 ∘C? The relevant values at 20 ∘C are included in the table.

vapor pressure: Torr

Consider the following reaction: CO(g)+H2O(g)⇌CO2(g)+H2(g) Kp=0.0611 at 2000 K A reaction mixture initially contains a CO partial pressure of 1390 torr and a H2O partial pressure of 1770 torr at 2000 K.

A) Calculate the equilibrium partial pressure of CO2.

Write equations for the half-reactions that occur at the anode and cathode for the electrolysis of each of the following aqueous solutions.

Part A Ni(NO3)2(aq) Express your answers as chemical equations separated by a comma. Identify all of the phases in your answer.

Part B KCl(aq) Express your answers as chemical equations separated by a comma. Identify all of the phases in your answer.

Part C CuBr2(aq) Express your answers as chemical equations separated by a comma. Identify all of the phases in your answer.

Consider the equilibrium between COBr₂, CO and Br₂.

• COBr₂(g) <-->CO(g) + Br₂(g) K = 2.08 at 382 K

The reaction is allowed to reach equilibrium in a 14.6-L flask. At equilibrium, [COBr₂] = 4.50×10^-2 M, [CO] = 0.306 M and [Br₂] = 0.306 M.
(a) The equilibrium mixture is transferred to a 7.30-L flask. In which direction will the reaction proceed to reach equilibrium? right or left

(b) Calculate the new equilibrium concentrations that result when the equilibrium mixture is transferred to a 7.30-L flask.

1. if a buffer has a 4 charge and it is involved in removing two hydrogen ions from a solution, the buffers charge will become:

2. How many times more basic is a solution with a pH of 9 compared to a solution with a pH of 2?

3. What is the term used when describing an electrolyte becoming individual ions?

A weak base B (neutral charge) is dissolved in water at a concentration of 0.500 M. The concentration of the resulting ions is 0.170. What is the numerical value of Kb? The answer should be written to 4 decimal places and correct within +/-0.0020. Don't forget that [B] is going to be less than 0.500 M.