Chapter 19: Q19.13P (page 873)

What are the $[H_{3} O^{+}]$ and the pH of a buffer that consists of 0.55M ${HNO}_{2}$ and0.75M ${KNO}_{2}$ ( $K_{a}$ of ${HNO}_{2} {= 7.1×10}^{- 4}$ )?

Short Answer

Expert verified

The pH of propanoic acid is 3.28 and the $[H_{3} O^{+}]$ obtained is $5.2 \times 10^{- 4}$ .

Step by step solution

Ionic Equilibrium

An ionic equilibrium refers to an equilibrium that exists in the solution of weak electrolytes between unionized molecules and ions.

What is H3O + and pH?

Write the 0.55 M ${HNO}_{2}$ dissociation equation first.

${HNO}_{2} {+H}_{2} O ⇌ N {O_{2}}^{-} {+H}_{3} O^{+} .$

Then, write the 0.75 M ${KNO}_{2}$ dissociation equation.

${KNO}_{2} \to N {O_{2}}^{-} {+K}^{+} .$

We now have the initial nitric acid and nitrate.

${HNO}_{2} = 0.55M {NO}_{2}^{-} = 0.75 M$

To find the pH, we may utilize the Henderson-Hasselbalch equation. First, solve for the ${pK}_{a}$ .

role="math" localid="1663406489385" ${pK}_{a} {= - logK}_{a} {= - log(7.1×10}^{- 4}) = 3.15 pH = pKa + log \frac{[{NO}_{2}^{-}]}{[{HNO}_{2}]} = 3.15 + log \frac{0.75 M}{0.55 M} = 3.28.$

Then, solve for $[H_{3} O^{+}]$ from the calculatedpHas:

$pH = - log [H_{3} O^{+}] [H_{3} O^{+}] {= 10}^{- pH} {= 10}^{- 3.28} {= 5.2×10}^{- 4}$

Therefore, the values obtained are:

$pH = 3.28. [H_{3} O^{+}] {= 5.2×10}^{- 4}$

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What are the $[H_{3} O^{+}]$ and the pH of a buffer that consists of 0.55M ${HNO}_{2}$ and0.75M ${KNO}_{2}$ ( $K_{a}$ of ${HNO}_{2} {= 7.1×10}^{- 4}$ )?

Short Answer

Step by step solution

Ionic Equilibrium

What is H3O + and pH?

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What are the [H3O+]and the pH of a buffer that consists of 0.55M HNO2and0.75M KNO2( KaofHNO2= 7.1×10-4 )?

Short Answer

Step by step solution

Ionic Equilibrium

What is H3O + and pH?

One App. One Place for Learning.

Most popular questions from this chapter

Recommended explanations on Chemistry Textbooks

Physical Chemistry

Kinetics

Inorganic Chemistry

Chemistry Branches

Chemical Analysis

Organic Chemistry

Study anywhere. Anytime. Across all devices.

What are the $[H_{3} O^{+}]$ and the pH of a buffer that consists of 0.55M ${HNO}_{2}$ and0.75M ${KNO}_{2}$ ( $K_{a}$ of ${HNO}_{2} {= 7.1×10}^{- 4}$ )?