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Equilibrium appeared 36 times across 3 years — 4.2% of Chemistry. This question is from Hydrolysis of Salts.

Year	2026	2025	2024	Total
Questions	10	18	8	36

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$Kₐ$ $K_a$ for $CH₃COOH$ $CH_3COOH$ is $1.8 \times 10⁻⁵$ $1.8 \times 10^{-5}$ and $Kb$ $K_b$ for $NH₄OH$ $NH_4OH$ is $1.8 \times 10⁻⁵$ $1.8 \times 10^{-5}$. The pH of ammonium acetate solution will be

Numerical Answer Type:

Enter a numerical value Answer: 7 to 7 +4 marks

Solution & Explanation

Related Formula

For a salt of weak acid and weak base (like ammonium acetate):

pH = (1)/(2) (pKw + pKₐ - pKb)

Core Logic

Ammonium acetate ( $CH₃COONH₄$ $CH_3COONH_4$) is a salt formed from a weak acid ( $CH₃COOH$ $CH_3COOH$) and a weak base ( $NH₄OH$ $NH_4OH$). Given: $Kₐ = 1.8 \times 10⁻⁵$ $K_a = 1.8 \times 10^{-5}$ $Kb = 1.8 \times 10⁻⁵$ $K_b = 1.8 \times 10^{-5}$

Since $Kₐ = Kb$ $K_a = K_b$, taking the negative logarithm gives $pKₐ = pKb$ $\mathrm{p}K_a = \mathrm{p}K_b$.

Step 1: Calculate pH

pH = pKw + pKₐ - pKb2

Substitute $pKₐ = pKb$ $\mathrm{p}K_a = \mathrm{p}K_b$:

pH = pKw2

At standard temperature (298 K), $pKw = 14$ $\mathrm{p}K_w = 14$.

pH = (14)/(2) = 7

Pattern Recognition

If $Kₐ = Kb$ $K_a = K_b$ for a weak acid-weak base salt, the hydrolysis of cation and anion perfectly balance out, making the resulting solution exactly neutral (pH = 7) regardless of the concentration of the salt.

Chapter Mix

Class 11 Chemistry: Equilibrium

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$Kₐ$ $K_a$ for $CH₃COOH$ $CH_3COOH$ is $1.8 \times 10⁻⁵$ $1.8 \times 10^{-5}$ and $Kb$ $K_b$ for $NH₄OH$ $NH_4OH$ is $1.8 \times 10⁻⁵$ $1.8 \times 10^{-5}$. The pH of ammonium acetate solution will be

Solution & Explanation

Related Formula

Core Logic

Step 1: Calculate pH

Pattern Recognition

Chapter Mix

Reference Study Guides

More Equilibrium Previous-Year Questions — Page 8

Solution

Related Formula

Core Logic

Chapter Mix

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Kₐ$K_a$ for CH₃COOH$CH_3COOH$ is 1.8 × 10⁻⁵$1.8 \times 10^{-5}$ and Kb$K_b$ for NH₄OH$NH_4OH$ is 1.8 × 10⁻⁵$1.8 \times 10^{-5}$. The pH of ammonium acetate solution will be

Solution & Explanation

Related Formula

Core Logic

Step 1: Calculate pH

Pattern Recognition

Chapter Mix

Reference Study Guides

More Equilibrium Previous-Year Questions — Page 8

Solution

Related Formula

Core Logic

Chapter Mix

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$Kₐ$ $K_a$ for $CH₃COOH$ $CH_3COOH$ is $1.8 \times 10⁻⁵$ $1.8 \times 10^{-5}$ and $Kb$ $K_b$ for $NH₄OH$ $NH_4OH$ is $1.8 \times 10⁻⁵$ $1.8 \times 10^{-5}$. The pH of ammonium acetate solution will be