You have isolated the enzyme sialidase from cell lysosomal extracts. This enzyme's activity is at its highest at pH 4.7. This pH is known as the enzyme's pH optimum. You need to study the activity of the protein in the laboratory a) Which buffer system would be the best buffer for you to use to assure the protein is the most active and why? Lactic Acid (CH3CH(OH)COOH and its conjugate base) pka 3.86 Carbonic acid (H₂CO3 and its conjugate base) pka 6.35 Phosphoric acid (H3PO4 and its conjugate base) pKa 2.14 b) Draw the disassociation of the acid you choose in water (labeling the acid form and its conjugate base) and determine the ratio of each you would need for your buffer.

What is the equilibrium constant for the following reaction that occurs when disodium citrate(Na2HC6H5O7) dissolves in water at 25ºC? The acid dissociation constants for citric acid, H3C6H5O7 , are:Ka1 = 7.4 × 10–4 , Ka2 =1.7 × 10–5 , and Ka3 = 4.0 × 10–7 . HC6H5O72– (aq) + H2O(l) ⇌ H2C6H5O7– (aq) + OH– (aq)

Calculate the pH at 25 °C of a 0.38M solution of trimethylammonium chloride pk of 4.19. Round your answer to 1 decimal place. pH = X Ś ((CH3),NHCI). Note that trimethylamine ((CH3)3 N is a weak base with a

PbI2 has a Ksp equal to 1.4 x 10-8. A 1.0 L saturated solution of PbI2 contains a concentration of I- equal to 3.0 x 10-3 M. If 500 mL of water is evaporated from the solution, what will be the concentration of Pb2+ after equilibrium is reestablished?      [Pb2+] = 1.5 x 10-3 M     [Pb2+] = 7.5 x 10-4 M     [Pb2+] = 3.0 x 10-3 M     [Pb2+] = 0 M (no ions will be in solution)

Use excel spreadsheet to solve the following results: A sorption study of Cd2+ on a loamy sand gave the following results: Equilibrium Concentration              Cd2+ Sorbed                (mg/L)                                 (mg/mg)           0.045.                                         10           0.10.                                           19           0.13.                                           27           0.20.                                          38           0.24.                                          47 what is the Kd ?

Time to purify biochemisfunase! To do this, you’ll need to make MORE buffers. One of the buffers that you need to make requires 150 mM Tris (pH 8), 250 mM sodium chloride (NaCl) and 2 mM dithiothreitol (DTT, a reducing agent that prevents the formation of disulfide bonds in proteins). Your jolly postdoc  friend wants you first to make 500 ml of a1.0M Tris stock solution before making the buffer. Describe how you would make this stock solution, and show all calculations.

6) When the reversible reaction HC;H;O2 (aq) E> H*(aq) + C2H3O2(aq) is at equilibrium at room temperature, pH of the reaction mixture is 5. What will be the change in pH when you add a large amount of solid acetate (C2H30,Na) to the reaction mixture? a) pH will not change because C2H;O,Na is not a part of the reaction equation. b) pH will not change because acetic acid and sodium acetate form a buffer c) pH will decrease because the reaction will shift towards reactants d) pH will increase because the reaction will shift towards reactants

Lactase is an enzyme that breaks down the sugar lactose which is commonly found in dairy products. Some people develop lactose intolerance as they grow older and the amount of lactase enzyme in their gut diminishes. Since the enzyme is commonly found in the gut of humans it can withstand a pH that is very acidic, ranging from a pH of 2-7. A student decided to do an experiment to determine how the pH of a solution affects lactase enzyme activity. Lactase works by breaking lactose into its two component sugars of glucose and galactose.   To conduct the experiment the student prepared a solution of lactose and placed it into 5 different test tubes. A pH buffer solution was then added to each test tube with a pH of 2.0 in the first tube, 4.0 in the second, 6.0 in the third, 8.0 in the fourth, and a 10 pH in the fifth. Next, the enzyme lactase was added in equal amounts to each test tube and allowed to sit for ten minutes white the enzyme reacted with the lactose. At the end of the ten…

The dissolution of borax is: Na2B4O5(OH)4 • 8H2O(s) ⇌ 2 Na+(aq) + B4O5(OH)42–(aq) + 8 H2O(l) In the lab, after filtering a 50.0 mL solution, a 7.00 mL aliquot was diluted to 28 mL. The solution was then titrated with 0.4 M HCl. The endpoint was reached after 5.0 mL titrant was added. Find the following (show your work): a. Concentration of tetraborate ions in the filtrate b. Molar solubility and Ksp of borax