Chapter 19: Q19.19P (page 873)

Find the pH of a buffer that consists of 0.25M ${NH}_{3}$ and 0.15M ${NH}_{4} Cl$ ( ${pK}_{b}$ of ${NH}_{3} = 4.75$ )?

Short Answer

Expert verified

The pH value is 9.47.

Step by step solution

Define Ionic Equilibrium

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

The pH of the given solution

Write the 0.25 M ${NH}_{3}$ dissociation equation first.

${NH}_{3} {+H}_{2} O ⇌ N {H_{3}}^{+} {+ OH}^{-} .$

Then write the 0.15 M ${NH}_{4} Cl$ dissociation equation.

${NH}_{4} Cl \to N {H_{4}}^{+} {+ Cl}^{-} .$

We now have the initial ammonia and ammonium concentrations.

${NH}_{3} = 0.25 M. N {H_{4}}^{+} = 0.15 M.$

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

role="math" localid="1663396782915" ${pK}_{w} {= pK}_{a} {+ pK}_{b} {pK}_{a} {= pK}_{w} {+ pK}_{b} = 14 - 4.75 = 9.25. pH = pKa + log \frac{[base]}{[acid]} = pKa + log \frac{[{NH}_{3}]}{[N {H_{4}}^{+}]} = 9.25 + log \frac{0.25 M}{0.15 M} = 9.47.$

Therefore, the pH value is 9.47.

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Find the pH of a buffer that consists of 0.25M ${NH}_{3}$ and 0.15M ${NH}_{4} Cl$ ( ${pK}_{b}$ of ${NH}_{3} = 4.75$ )?

Short Answer

Step by step solution

Define Ionic Equilibrium

The pH of the given solution

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Find the pH of a buffer that consists of 0.25MNH3and 0.15MNH4Cl(pKbofNH3= 4.75)?

Short Answer

Step by step solution

Define Ionic Equilibrium

The pH of the given solution

One App. One Place for Learning.

Most popular questions from this chapter

Recommended explanations on Chemistry Textbooks

Kinetics

Nuclear Chemistry

Physical Chemistry

Chemical Analysis

Inorganic Chemistry

Organic Chemistry

Study anywhere. Anytime. Across all devices.

Find the pH of a buffer that consists of 0.25M ${NH}_{3}$ and 0.15M ${NH}_{4} Cl$ ( ${pK}_{b}$ of ${NH}_{3} = 4.75$ )?