Chapter 9: Q36P (page 209)

Write the Henderson-Hasselbalch equation for a solution of formic acid. Calculate the quotient $[{HCO}_{2}^{-}] / [{HCO}_{2} H]$ at (a) $pH 3.000$ ; (b) $pH 3.744$ ; (c) $pH 4.000$ .

Short Answer

Expert verified

The Henderson-Hasselbalch equation is $pH = {pK}_{a} + \log ([A^{-}]) / [HA]$ .

a) $0.180$

b) $1.000$

c) $1.800$

Step by step solution

Definition of Henderson-Hasselbalch.

The Henderson-Hasselbalch equation is an approximate formula that demonstrates the link between a solution's pH or pOH, the ${pK}_{a}$ or ${pK}_{b}$ , and the ratio of dissociated chemical species concentrations

The Henderson-Hasselbalch equation for a solution of formic acid.

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

The quotient.

Find that quotient $[{HCO}_{2}^{-}] / [{HCO}_{2} H]$ has the $p K_{a} = 3.744$ and rearrange the equation to:

localid="1654866284447" $p H = p K_{a} + \log ([A^{-}] / [H A]) p H - p K = \log ([A^{-}] / [H A]) 10^{p H - p K_{a} =} ([A^{-}] / [H A]) a) W h e n p H = 3.000 10^{3.000 - 3.744} = ([A^{-}] / [H A]) 0.180 = ([A^{-}] / [H A]) b) W h e n p H = 3.744 10^{p H - p K_{a} =} ([A^{-}] / [H A]) 10^{3.744 - 3.744} = ([A^{-}] / [H A]) 1.000 = ([A^{-}] / [H A]) c) W h e n p H = 4.000 10^{p H - p K_{a} =} ([A^{-}] / [H A]) 10^{4.000 - 3.744} = ([A^{-}] / [H A]) 1.800 = ([A^{-}] / [H A])$

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Write the Henderson-Hasselbalch equation for a solution of formic acid. Calculate the quotient $[{HCO}_{2}^{-}] / [{HCO}_{2} H]$ at (a) $pH 3.000$ ; (b) $pH 3.744$ ; (c) $pH 4.000$ .

Short Answer

Step by step solution

Definition of Henderson-Hasselbalch.

The Henderson-Hasselbalch equation for a solution of formic acid.

The quotient.

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Write the Henderson-Hasselbalch equation for a solution of formic acid. Calculate the quotient [HCO2-]/[HCO2H]at (a) pH3.000; (b) pH3.744; (c)pH4.000.

Short Answer

Step by step solution

Definition of Henderson-Hasselbalch.

The Henderson-Hasselbalch equation for a solution of formic acid.

The quotient.

One App. One Place for Learning.

Most popular questions from this chapter

Recommended explanations on Chemistry Textbooks

Chemistry Branches

The Earths Atmosphere

Inorganic Chemistry

Kinetics

Ionic and Molecular Compounds

Physical Chemistry

Study anywhere. Anytime. Across all devices.

Write the Henderson-Hasselbalch equation for a solution of formic acid. Calculate the quotient $[{HCO}_{2}^{-}] / [{HCO}_{2} H]$ at (a) $pH 3.000$ ; (b) $pH 3.744$ ; (c) $pH 4.000$ .