Ionic Equilibrium

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Q1. If the pKa of acetic acid is 4.76, what is the pH of a 0.1 M solution?

Solution:

For a weak acid, pH ≈ pKa for a 0.1 M solution, so pH ≈ 4.76.

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Q2. Calculate the pH of a 0.1 M NaOH solution.

Solution:

pOH = -log[OH-] = -log(0.1) = 1, thus pH = 14 - pOH = 14 - 1 = 13.

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Q3. What is the pH of a solution that is 0.01 M in both HCl and NaOH?

Solution:

HCl and NaOH neutralize each other, resulting in a neutral solution with pH = 7.

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Q4. What is the concentration of H+ ions in a solution with pH 4?

Solution:

[H+] = 10^(-pH) = 10^(-4) = 0.0001 M.

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Q5. What is the pH of a buffer solution made from 0.1 M acetic acid and 0.1 M sodium acetate? (2023)

Solution:

Using the Henderson-Hasselbalch equation, pH = pKa + log([A-]/[HA]) = 4.74 + log(1) = 4.74.

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Q6. What is the pH of a solution with [H+] = 1 x 10^-7 M? (2023)

Solution:

pH = -log[H+] = -log(1 x 10^-7) = 7.

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Q7. What is the effect of adding a common ion on the solubility of a salt? (2020)

Solution:

Adding a common ion decreases the solubility of a salt due to the common ion effect, which shifts the equilibrium to the left.

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Q8. If 0.1 M acetic acid has a pH of 2.87, what is the concentration of H+ ions?

Solution:

[H+] = 10^(-pH) = 10^(-2.87) ≈ 0.001 M.

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Q9. What is the pH of a solution with [H+] = 0.00001 M?

Solution:

pH = -log(0.00001) = 5.

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Q10. In a buffer solution, which of the following components is essential? (2023)

Solution:

A buffer solution is made from a weak acid and its conjugate base (salt), which helps maintain pH.