If a chemist wishes to prepare a buffer that will be effective at a pH of 3.00 at 25°C,the best choice would be an acid component with a K_a equal to A) 9.10 × 10^-2. B) 9.10 × 10^-4. C) 9.10 × 10^-6. D) 9.10 × 10^-8. E) 9.10 × 10^-10.

Question

Quizplus · Accepted Answer

A buffer is most effective when the pH is close to the pKa of the acid. The pKa is calculated as -log(Ka). For a pH of 3.00, the pKa should also be around 3.00, which corresponds to a Ka of 10^-3. The closest value is 9.10 × 10^-4.

If a Chemist Wishes to Prepare a Buffer That Will