91Ó°ÊÓ

Draw electron-dot structures for the following molecules, indicatingany unshared electron pairs. Which of the compounds are likely to actas Lewis acids and which as Lewis bases?

(a)${\mathbf{AlBr}}_3$(b) ${\mathbf{CH}}_3{\mathbf{CH}}_2{\mathbf{NH}}_2$(c)${\mathbf{BH}}_3$

(d)HF (e)${\mathbf{CH}}_3{\mathbf{SCH}}_3$(f)${\mathbf{TiCl}}_4$

Write the products of the following acid–base reactions:$\begin{array}{l}\left(a\right)C{H}_{3}OH+H_{2}S{O}_4⇄?\\ \left(b\right)C{H}_{3}OH+NaN{H}_2⇄?\\ \left(c\right)C{H}_{3}N{H_3}^{+}+C{l}^{-}+NaOH⇄?\end{array}$

Rank the following substances in order of increasing acidity:

Which, if any, of the substances in Problem 2-44 is a strong enough acidto react almost completely with NaOH? (The $\mathbf{p}{K}_a$ of is 15.74.)

The ammonium ion ( ${{\mathbf{NH}}_4}^{+}$, pK_a=9.25) has a lower pKa than the

methylammoniumion (${\mathbf{CH}}_3{{\mathbf{NH}}_3}^{+}$ , pK_a=10.66). Which is the stronger

base, ammonia $\left({\mathbf{NH}}_3\right)$or methylamine $\left({\mathbf{CH}}_3{\mathbf{NH}}_2\right)$ ? Explain.

Is tert-butoxide anion a strong enough base to react significantly with

water? In other words, can a solution of potassium tert-butoxide be

prepared in water? The pK_a of tert-butyl alcohol is approximately 18.

Predict the structure of the product formed in the reaction of the organic base pyridine with the organic acid acetic acid, and use curved arrowsto indicate the direction of electron flow.

Calculate values from the following ’s:

(a)Acetone, $p{K}_a$=19.3 (b)Formic acid, $p{K}_a$=3.75

Calculate values from the following ’s:

(a)Nitromethane, $K_a$=$\mathbf{5}\mathbf{.}\mathbf{0}\mathbf{×}{\mathbf{10}}^{-11}$

(b)Acrylic acid, $K_a$=$\mathbf{5}\mathbf{.}\mathbf{6}\mathbf{×}{\mathbf{10}}^{-5}$

What is the pH of a 0.050 M solution of formic acid, $\text{p}{K}_a$=3.75?