Chapter 2: Q16. (page 40)

What is the pK of the weak acid HA if a solution containing 0.1 M HA and 0.2 M A⁻ has a pH of 6.5?

Short Answer

Expert verified

The pK value of the solution is 6.2.

Step by step solution

Introduction of Hasselbach-Henderson equation.

The Hasselbach-Henderson equation states that when the molar concentration of an acid (HA) and its conjugate base (A^-) are equal, then

$\log \frac{[A]}{[HA]} = \log 1 = 0$ and hence, the pH value of the solution is equal to the pK value.

Mathematically,

$pH = pK + \log \frac{[A^{-}]}{[HA]}$

(i)

Calculation of the pK value of the solution.

Substitute $0.2 M$ for $[A^{-}], 0.1 M for [HA]$ , and 6.5 for pH.

$6.5 = pK + \log (\frac{0.2 M}{0.1 M}) 6.5 = pK + \log 2 pK = 6.5 - 0.3 = 6.2$

Therefore, the pK value of the final solution is 6.2.

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What is the pK of the weak acid HA if a solution containing 0.1 M HA and 0.2 M A⁻ has a pH of 6.5?

Short Answer

Step by step solution

Introduction of Hasselbach-Henderson equation.

Calculation of the pK value of the solution.

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What is the pK of the weak acid HA if a solution containing 0.1 M HA and 0.2 M A− has a pH of 6.5?

Short Answer

Step by step solution

Introduction of Hasselbach-Henderson equation.

Calculation of the pK value of the solution.

One App. One Place for Learning.

Most popular questions from this chapter

Recommended explanations on Biology Textbooks

Biological Structures

Cell Communication

Communicable Diseases

Biology Experiments

Energy Transfers

Microbiology

Study anywhere. Anytime. Across all devices.

What is the pK of the weak acid HA if a solution containing 0.1 M HA and 0.2 M A⁻ has a pH of 6.5?