Chapter 19: Q19.26P (page 873)

What is the component concentration ratio, $[{CH}_{3} {COO}^{-}] / [{CH}_{3} COOH]$ , of a buffer that has a pH of 4.39 ( $K_{a}$ of $[{CH}_{3} COOH] = 1.8 \times 10^{- 5}$ )?

Short Answer

Expert verified

The component concentration ratio obtained is $\frac{[{CH}_{3} {COO}^{-}]}{[{CH}_{3} COOH]} = 0.45.$ $\frac{[{CH}_{3} {COO}^{-}]}{[{CH}_{3} COOH]} = 0.45.$

Step by step solution

Buffer solution

The pH value of an acidic buffer solution can be determined by using the formula below:

$pH = pKa + \log \frac{[salt]}{[acid]}$

Explanation

First, write the ${CH}_{3} COOH$ dissociation process.

${CH}_{3} {COOH +H}_{2} O ⇌ H_{3} O^{+} {+ CH}_{3} {COO}^{-} .$

We must alter the Henderson-Hassle Balch equation for solving $\frac{[{CH}_{3} {COO}^{-}]}{[{CH}_{3} COOH]}$ . The pH and $K_{a}$ are given. Therefore, first solve for the ${pK}_{a}$ .

${pK}_{a} {= - logK}_{a} = - \log (1.8 \times 10^{- 5}) = 4.74$

Then alter the Henderson-Hassle Balch equation to find the answer for

$\frac{[{CH}_{3} {COO}^{-}]}{[{CH}_{3} COOH]} .$

role="math" ${pH = pK}_{a} + log \frac{[{CH}_{3} {COO}^{-}]}{[{CH}_{3} COOH]} log \frac{[{CH}_{3} {COO}^{-}]}{[{CH}_{3} COOH]} {= pH - pK}_{a} \frac{[{CH}_{3} COO -]}{[{CH}_{3} COOH]} {= 10}^{{pH - pK}_{a}} {= 10}^{4.39 - 4.74} = 0.45.$

Therefore, the component concentration ratio obtained is $\frac{[{CH}_{3} {COO}^{-}]}{[{CH}_{3} COOH]} = 0.45$ .

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What is the component concentration ratio, $[{CH}_{3} {COO}^{-}] / [{CH}_{3} COOH]$ , of a buffer that has a pH of 4.39 ( $K_{a}$ of $[{CH}_{3} COOH] = 1.8 \times 10^{- 5}$ )?

Short Answer

Step by step solution

Buffer solution

Explanation

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What is the component concentration ratio, [CH3COO-]/[CH3COOH], of a buffer that has a pH of 4.39 ( Kaof [CH3COOH]=1.8×10-5)?

Short Answer

Step by step solution

Buffer solution

Explanation

One App. One Place for Learning.

Most popular questions from this chapter

Recommended explanations on Chemistry Textbooks

Nuclear Chemistry

Kinetics

Organic Chemistry

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The Earths Atmosphere

Study anywhere. Anytime. Across all devices.

What is the component concentration ratio, $[{CH}_{3} {COO}^{-}] / [{CH}_{3} COOH]$ , of a buffer that has a pH of 4.39 ( $K_{a}$ of $[{CH}_{3} COOH] = 1.8 \times 10^{- 5}$ )?