Chapter 9: Q40P (page 209)

How many milliliters of $0.246 {MHNO}_{3}$ should be added to $213 mL$ of $0.00666 M 2,$ -bipyridine to give a pH of $4.19$ ?

Short Answer

Expert verified

$3.38 mL of 0.246 {MHNO}_{3}$ should be added to $213 mL$ of $0.00666 M 2, 2^{'}$ -bipyridine to give a pH of $4.19$ .

Step by step solution

Concept used.

The pH of the buffer determined by the concentration ratio of $[A^{-}] and [HA]$ by the following Henderson-Hasselbalch equation: $pH = {pK}_{a} \log ([A^{-}] / [HA])$

The milliliters of 0.246MHNO3should be added to 213mLof 0.00666M2,2'bipyridine to give a pH of 4.19.

First, figure out how many moles of $2, 2$ -bipyridine there are:

localid="1654854344602" role="math" $moles of 2, 2 - bipyridine = concentration \times volume = 0.00666 M \times 213 mL = 1.419 mmol$

Consider the following reaction,

$2, 2 - bipyridine + H^{+} \to 2, 2 - bipyridine + H^{+} [2, 2 - bipyridine] = 1.419 - x [H^{+}] = [2, 2 - bipyridine + H^{+}] = x$

The pH of the buffer,

$pH = {pK}_{a} + \log ([A^{-}] / [HA]) pH = {pK}_{a} + \log ([2, 2 - bipyridine] / [2, 2 - {bipyridineH}^{+}]) 4.19 = 4.34 + \log ((1.419 - x) / x) x = 0.831 mmol Now calculate the volume of 0.246 {MHNO}_{3} in millilitres : volume = moles / concentration = 0.831 m ol / 0.246 M = 3.38 mL$

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How many milliliters of $0.246 {MHNO}_{3}$ should be added to $213 mL$ of $0.00666 M 2,$ -bipyridine to give a pH of $4.19$ ?

Short Answer

Step by step solution

Concept used.

The milliliters of 0.246MHNO3should be added to 213mLof 0.00666M2,2'bipyridine to give a pH of 4.19.

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How many milliliters of 0.246MHNO3should be added to 213mLof0.00666M2,-bipyridine to give a pH of4.19?

Short Answer

Step by step solution

Concept used.

The milliliters of 0.246MHNO3should be added to 213mLof 0.00666M2,2'bipyridine to give a pH of 4.19.

One App. One Place for Learning.

Most popular questions from this chapter

Recommended explanations on Chemistry Textbooks

Physical Chemistry

Chemical Reactions

Making Measurements

Inorganic Chemistry

The Earths Atmosphere

Chemical Analysis

Study anywhere. Anytime. Across all devices.

How many milliliters of $0.246 {MHNO}_{3}$ should be added to $213 mL$ of $0.00666 M 2,$ -bipyridine to give a pH of $4.19$ ?