Question

Normally the bicarbonate concentration is about 24 mEq/L and the carbonic acid concentration is about 1.2; pKa = 6.1. Using the equation pH + log [salt]/[acid], calculate the pH.

a. 7.28
b. 7.38
c. 7.40
d. 17.42

Answer 1

The pH of the solution, using the Henderson-Hasselbalch equation with the given bicarbonate and carbonic acid concentrations and the pKa value, is calculated to be approximately 7.40.

Step-by-step explanation:

Using the Henderson-Hasselbalch equation, the pH of a solution can be calculated when the concentrations of acid and its conjugate base are known. Given that the bicarbonate concentration is about 24 mEq/L (0.024 M) and the carbonic acid concentration is about 1.2 mEq/L (0.0012 M), and using the provided pKa value of 6.1 (presumably at body temperature), we can substitute these values into the equation:

pH = pKa + log(¡base]/[acid])

pH = 6.1 + log(0.024/0.0012)

pH = 6.1 + log(20)

pH = 6.1 + 1.3010 (the log of 20)

pH = 7.4010

Therefore, the pH of the solution is closest to option c, which is 7.40.