1.11: Practice Problems for Bronsted-Lowry Acid-Base Chemistry

Last updated
Save as PDF

Page ID: 218645

\( \newcommand{\vecs}[1]{\overset { \scriptstyle \rightharpoonup} {\mathbf{#1}} } \) \( \newcommand{\vecd}[1]{\overset{-\!-\!\rightharpoonup}{\vphantom{a}\smash {#1}}} \)\(\newcommand{\id}{\mathrm{id}}\) \( \newcommand{\Span}{\mathrm{span}}\) \( \newcommand{\kernel}{\mathrm{null}\,}\) \( \newcommand{\range}{\mathrm{range}\,}\) \( \newcommand{\RealPart}{\mathrm{Re}}\) \( \newcommand{\ImaginaryPart}{\mathrm{Im}}\) \( \newcommand{\Argument}{\mathrm{Arg}}\) \( \newcommand{\norm}[1]{\| #1 \|}\) \( \newcommand{\inner}[2]{\langle #1, #2 \rangle}\) \( \newcommand{\Span}{\mathrm{span}}\) \(\newcommand{\id}{\mathrm{id}}\) \( \newcommand{\Span}{\mathrm{span}}\) \( \newcommand{\kernel}{\mathrm{null}\,}\) \( \newcommand{\range}{\mathrm{range}\,}\) \( \newcommand{\RealPart}{\mathrm{Re}}\) \( \newcommand{\ImaginaryPart}{\mathrm{Im}}\) \( \newcommand{\Argument}{\mathrm{Arg}}\) \( \newcommand{\norm}[1]{\| #1 \|}\) \( \newcommand{\inner}[2]{\langle #1, #2 \rangle}\) \( \newcommand{\Span}{\mathrm{span}}\)\(\newcommand{\AA}{\unicode[.8,0]{x212B}}\)

1. For each of the species below, identify the most acidic proton and provide the structure of the corresponding conjugate base. You might want to draw detailed Lewis formulas in some cases.

2. For each of the species below, identify the basic atom and provide the structure of the corresponding conjugate acid. You might want to draw detailed Lewis formulas in some cases.

3. Fill in the reactants or products for the following acid-base reactions. Keep in mind that in line-angle formulas hydrogens are not shown. When in doubt, write complete Lewis structures. Abbreviations used: Ph=phenyl (a benzene ring attached to a carbon chain)

4. Arrange the substances by order of acidity or basicity as indicated. You may use pKa tables, periodic tables, or any other tools available to you (except for your cell phone).

5. Circle the side favored by equilibrium in the following acid-base reactions.

6. The conjugate acid of ammonia, NH₃, is:

A) NH₄ ⁺ B) NH₂OH C) NH₂ ^- D) none of the above

7. Methanesulfonic acid, CH₃SO₃H, has a pK_a of -7 while ethanol, CH₃CH₂OH, has a pK_a of 15.9. Which is the stronger acid and what accounts for this large difference in relative acidity?

8. Would you predict trifluoromethanesulfonic acid, CF₃SO₃H, to be a stronger or weaker acid than methanesulfonic acid, CH₃SO₃H? Explain your reasoning.

9. Consider the species CH₃O^-, NH₂ ^-, and CH₃COO^-. Rank these ions in order of increasing basicity, and explain your rationale.

10. The K_a of formic acid is 1.7 x 10^-4. The pK_a of formic acid is __________.

A) 1.7 B) 10.3 C) 4.0 D) 3.8 E) -2.3

11. Provide the structure of the conjugate base of phenol (shown below) and all its resonance forms.

12. Rank the following in order of increasing acidity: CH₃OH, HCl, NH₃, and CH₄.

13. Rank the following in order of increasing basicity: CH₃O^-, H₂N^-, H₂O, and NH₃.

14. When methanol (CH₃OH) acts as a base, its conjugate acid is __________. A) CH₄OH B) CH₃OH₂⁺ C) CH₄O⁺ D) CH₃O- E) ^-CH₂OH

15. Which of the following pairs of bases lists the stronger base first?

A) H₂O > HO^-

B) H₂N^- > CH₃COO^-

C) CH₃COO- > HO^-

D) I^- > Cl^-

E) HO^- > H₂N^-

16. Draw the structure of the conjugate acid of acetone (CH₃COCH₃).