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Buffer composition needed for a given pH (Henderson equation)

This type of question, asked 6 times: 28 Jun 2022, 26 Jul 2022, 24 Jan 2023, 30 Jan 2024, 22 Jan 2026 S2, 28 Jan 2026 S1. All 6 questions below, oldest first.

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  1. Question 1

    28 Jun 2022

    124
    A student needs to prepare a buffer solution of propanoic acid and its sodium salt with pH4pH4. The ratio of [CH3CH2COO−][CH3CH2COOH]\frac{\left\lbrack CH_{3}CH_{2}COO^{-} \right\rbrack}{\left\lbrack CH_{3}CH_{2}COOH \right\rbrack} required to make buffer is Given: Ka(CH3CH2COOH)=1.3×10−5K_{a}\left( CH_{3}CH_{2}COOH \right)= 1.3 \times10^{- 5}

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  2. Question 2

    26 Jul 2022

    123
    Class XII students were asked to prepare one litre of buffer solution of pH8.26pH8.26 by their chemistry teacher. The amount of ammonium chloride to be dissolved by the student in 0.2M0.2M ammonia solution to make one litre of the buffer is (Given pKb(NH3)=4.74pK_{b}\left( NH_{3} \right)= 4.74; Molar mass of NH3=17 g mol−1NH_{3}= 17\text{ }g{\text{ }mol}^{- 1}; Molar mass of NH4Cl=53.5 g mol−1NH_{4}Cl = 53.5\text{ }g{\text{ }mol}^{- 1} )

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  3. Question 3

    24 Jan 2023

    57
    The dissociation constant of acetic acid is x×10−5x \times10^{- 5}. When 25 mL25\text{ }mL of 0.2MCH3COONa0.2MCH_{3}COONa solution is mixed with 25 mL25\text{ }mL of 0.02MCH3COOH0.02MCH_{3}COOH solution, the pHpH of the resultant solution is found to be equal to 5 . The value of xx is

  4. Question 4

    30 Jan 2024

    145
    The pHpH of an aqueous solution containing 1M1M benzoic acid (pKa=4.20)\left( pK_{a}= 4.20 \right) and 1M1M sodium benzoate is 4.5. The volume of benzoic acid solution in 300 mLmL of this buffer solution is ______ mLmL.

  5. Question 5

    22 Jan 2026 S2

    38
    Which of the following mixture gives a buffer solution with pH=9.25pH = 9.25 ? Given : pKb(NH4OH)=4.75pK_{b}\left( NH_{4}OH \right)= 4.75

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  6. Question 6

    28 Jan 2026 S1

    31
    Consider a weak base ' B ' of pKb=5.699pK_{b}= 5.699. ' x ' mL of 0.02 M HCl and ' y ' mL of 0.02 M weak base ' B ' are mixed to make 100 mL of a buffer of pH 9 at 25∘C25^{\circ}C. The values of ' xx ' and ' yy ' respectively are: [Given: log⁡2=0.3010,log⁡3=0.4771,log⁡5=0.699\log2 = 0.3010,\log3 = 0.4771,\log5 = 0.699 ]

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