Acid Base Chemistry (Dr.Miles TAMU)

Question 1

Formula to calculate pH or pKa

Answer 1

• pH = pKa+log([CB]/[CA])
• pKa = pH-log([CB]/[CA])

Question 2

Titration Curves

Answer 2

A titration is an analytical method used to determined the amount of acid in solution.
- equilibrium constant of 10^14 meaning all hydrogen atoms are converted to water

Question 3

Polyprotic acids

Answer 3

Substances that have more than one dissociable proton. Removing each hydrogen constitutes a separate equilibrium and there are many equilibria as dissociable protons

Question 4

Buffers

Answer 4

Buffers are solutions that resist pH changes as acid or base is added. Typically buffers are composed of a mixture of a weak acid and its conjugate base

Question 5

What are the two important physiological buffers and the function

Answer 5

• The phosphate buffer system maintains the pH in the cytosol of cells and consists of the monobasic, H2PO4- as the proton donor and the dibasic HPO4-2 as the proton acceptor
• the bicarbonate system which consists of carbonic acid (H2 CO3 ) as the proton donor and bicarbonate HCO3 as the proton acceptor and buffers the blood plasma

Question 6

How does the bicarbonate system increase the pH of the blood during exercis

Answer 6

1. Since the tissues produce H+ they are then passed to the blood stream. The increased hydrogen ion concentration shifts the equilibria of reaction 1 towards H2 CO 3 formation. The increased concentration ofH2 CO3 increases the concentration of CO2 (d) via the equilibrium of reaction
2. The increased concentration of CO2 (d) increases the concentration of CO2 (g) in the lungs as the result of reaction
   3.The excess CO2 (g) is exhaled.

Question 7

How does the bicarbonate system decrease the pH of the blood during exercise

Answer 7

1. As the hydrogen ion concentration decreases, the equilibrium of reaction 1 lowers the concentration of H2 CO3 . The decreased concentration of H2 CO3 produces a decrease in the concentration of CO2 (d) by the equilibrium of reaction
2. The decrease in CO2 (d) concentration will cause more CO2 (g) from the lungs to dissolve in the blood plasma (equilibrium 3)