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pH of an acidic buffer from Ka or pKa and the salt and acid concentrations (Henderson equation)

This type of question, asked 16 times: 2 May 2023 S1, 3 May 2023 S1, 4 May 2023 S1, 9 May 2023 S2, 10 May 2023 S2, 11 May 2023 S1, 9 May 2024 S1, 10 May 2024 S2, 12 May 2024 S1, 12 May 2024 S2, 19 Apr 2025 S2, 20 Apr 2025 S1, 13 Apr 2026 S2, 20 Apr 2026 S2, 15 May 2026 S1, 19 May 2026 S2. All 16 questions below, oldest first.

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  1. Question 1

    2 May 2023 S1

    67
    What is the ratio of concentration of salt to concentration of weak acid in buffer solution to maintain its pH value 7.2 (pKa=6.2)7.2\,\text{(pK}_a = 6.2\text{)}.

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  2. Question 2

    3 May 2023 S1

    100
    Calculate the pH of buffer solution containing 0.027 M weak acid and 0.054 M of its salt with strong base if pKapK_a is 4.2.

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  3. Question 3

    4 May 2023 S1

    68
    Calculate the pH of a buffer solution containing 0.35 M weak acid and 0.70 M of its salt with strong base if pKa\text{p}K_a is 4.56.

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  4. Question 4

    9 May 2023 S2

    95
    Calculate the pH of buffer solution containing 0.04 M NaF and 0.02 M HF (pKa_a = 3.142).

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  5. Question 5

    10 May 2023 S2

    70
    A buffer solution contains equal concentrations of weak acid and its salt with strong base. Calculate pH of buffer solution if dissociation constant of weak acid is 1.8×10−51.8 \times 10^{-5}.

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  6. Question 6

    11 May 2023 S1

    78
    A buffer solution is prepared by mixing 0.01 M HCN and 0.02 M NaCN. If KaK_a for HCN is 6.6×10−106.6 \times 10^{-10}, what is the concentration of H+H^+ ions in solution?

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  7. Question 7

    9 May 2024 S1

    65
    The buffer solution is prepared by mixing 0.2 M sodium acetate and 0.1 M acetic acid. If pKapK_a for acetic acid is 4.7, find the pH.

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  8. Question 8

    10 May 2024 S2

    51
    Calculate the pH of a buffer solution containing 0.01 M salt and 0.004 M weak acid (pKa=4.762pK_a=4.762)

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  9. Question 9

    12 May 2024 S1

    68
    What is pH of solution containing 50 mL each of 0.1 M sodium acetate and 0.01 M acetic acid? (pKa(CH3COOH)=4.50pK_a(\text{CH}_3\text{COOH})=4.50)

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  10. Question 10

    12 May 2024 S2

    65
    A buffer solution is prepared by mixing 0.01 M weak acid and 0.05 M solution of a salt of weak acid and strong base. What is the pH of buffer solution? (pKa = 4.74)

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  11. Question 11

    19 Apr 2025 S2

    64
    What is the pH of buffer solution prepared by mixing 0.01 M weak acid and 0.02 M salt of weak acid with strong base? (pKa=4.680)\left( pK_{a}= 4.680 \right)

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  12. Question 12

    20 Apr 2025 S1

    81
    What is the pH of buffer solution formed by mixing 0.01 M acetic acid and 0.05 M sodium acetate? (pKa=4.7447)\left( pK_{a}= 4.7447 \right)

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  13. Question 13

    13 Apr 2026 S2

    9
    Find the pH of a solution formed by mixing equal volume of solution of 0.10.1 M sodium propionate and 0.10.1 molar propionic acid. (Given The dissociation constant of propionic acid is 1.3×10−51.3 \times 10^{-5})

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  14. Question 14

    20 Apr 2026 S2

    9
    Calculate the pH of buffer solution containing 0.1M CH3COOH\mathrm{CH_3COOH} and 0.1 M CH3COONa\mathrm{CH_3COONa} [Ka=1.8×10−5][K_a = 1.8 \times 10^{-5}]

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  15. Question 15

    15 May 2026 S1

    9
    Calculate the pH of buffer solution containing 0.020.02 M weak acid and 0.040.04 M its salt with a strong base. [Ka=7.2×10−4K_a = 7.2 \times 10^{-4}]

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  16. Question 16

    19 May 2026 S2

    9
    What is the pH of a mixture of 4040 ml of 0.10.1 M Ba(HCOO)2\mathrm{Ba(HCOO)_2} and 2020 ml of 0.10.1 M HCOOH\mathrm{HCOOH} solution? (pKapK_a for formic acid =5= 5)

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