Question

The Ka of formic acid (HCOOH) is 1.8 × 10⁻⁴. What is the pKb of the formate ion?

Answer 1

The pKb of the formate ion can be calculated using the formula pKw = pKa + pKb. Given the Ka of formic acid, we can substitute it into the formula to find the pKb of the formate ion. The pKb is approximately 10.75.

Step-by-step explanation:

The pKb of the formate ion can be calculated from the Ka of formic acid using the equation pKw = pKa + pKb, where pKw is the negative logarithm of the ion product constant of water (1 × 10^-14 at 25°C). Since we know the Ka of formic acid is 1.8 × 10⁻⁴, we can calculate the pKb of the formate ion:

pKw = pKa + pKb

1 × 10^-14 = -log(1.8 × 10⁻⁴) + pKb

pKb = -log(1 × 10^-14) - (-log(1.8 × 10⁻⁴))

pKb ≈ 10.75