Exam 2: The Matrix of Life: Weak Interactions in an Aqueous Environment

You have been asked to determine the pK_a of an unknown acid. In a solution at pH 7.0, you find that 24% of the acid is in its deprotonated form. What is the pK_a of the acid?

Which of the following is the conjugate acid of hydrogen phosphate, HPO₄^2-?

Glutamic acid contains two carboxylic acid groups (pK_a values of 2.2 and 4.2)and an amine group (pK_a 9.7). What is the pI for glutamic acid?

Use the equilibrium equation of the blood buffer to predict what would happen to blood pH if respiration were to slow significantly.

What pH range is generally considered to be the physiological pH range?

What solution conditions are required for a protein to be a positively charged macroion?

Given the structure of a glucose molecule, which of the following explains the hydrogen bonding between glucose and water?

Which of the following acids or bases is least likely to be encountered in a biochemical setting?

If a buffer is made with the pH below the pK_a of the weak acid, the ratio of [base]/[acid] will be:

Which of the following atoms could interact through a hydrogen bond?

If gastric juice has a pH of about 1.5, which of the following would be predominantly deprotonated in the stomach?

Lysine contains two amine groups (pK_a values of 9.0 and 10.0)and a carboxylic acid group (pK_a 2.2). In a solution of pH 9.5, which of the following would best describe the protonation and charge state of lysine?

Lactic acid is a common product of actively working muscle. It is transported via the bloodstream to the liver. What percent of lactic acid is ionized in the bloodstream if the pH is 7.40 and the pK_a is 3.86?

Citric acid is a triprotic acid with three carboxylic acid groups having pK_a values of 3.1, 4.8, and 6.4. If a solution of citric acid has a pH of 5.5, what can be said about the predominant protonation state of the citric acid?

Since pK_a = -log K_a, which of the following is a correct statement?

Which of the following best explains the hydrogen bonding that occurs in water?

Imidazole is a commonly used buffer in biochemistry labs. With a pK_a of 7.0, what would be the ratio of base to acid at pH 7.4?

Which of the following would likely form micelles in an aqueous solution?

Formic acid is the active agent in an ant bite. What is the ratio of base/acid for formic acid (pK_a 3.9)in the blood stream at pH 7.4?

In the following titration curve, what does the inflection point represent?