Problem 133 - Chemistry

Question

Identify the Lewis acid and the Lewis base in each of the following reactions. a. \(\mathrm{B}(\mathrm{OH})_{3}(a q)+\mathrm{H}_{2} \mathrm{O}(l) \rightleftharpoons \mathrm{B}(\mathrm{OH})_{4}^{-}(a q)+\mathrm{H}^{+}(a q)\) b. \(\mathrm{Ag}^{+}(a q)+2 \mathrm{NH}_{3}(a q) \rightleftharpoons \mathrm{Ag}\left(\mathrm{NH}_{3}\right)_{2}^{+}(a q)\) c. \(\mathrm{BF}_{3}(g)+\mathrm{F}^{-}(a q) \rightleftharpoons \mathrm{BF}_{4}^{-}(a q)\)

Step-by-Step Solution

Answer

In conclusion, for each reaction: a. \( B(OH)_3 \) is the Lewis acid and \( H_2O \) is the Lewis base. b. \( Ag^+ \) is the Lewis acid and \( NH_3 \) is the Lewis base. c. \( BF_3 \) is the Lewis acid and \( F^- \) is the Lewis base.

Step 1: Identify electron pair donor and acceptor

In the reaction, B(OH)3 accepts an electron pair from H2O to form B(OH)4^-. At the same time, H2O donates a proton H^+. \( \mathrm{B}(\mathrm{OH})_{3} + \mathrm{OH}^{-} \rightleftharpoons \mathrm{B}(\mathrm{OH})_{4}^{-} \)

Step 2: Determine Lewis acid and base

B(OH)3 is the Lewis acid as it accepts an electron pair from the water molecule. H2O is the Lewis base as it donates an electron pair to the B(OH)3. #b. Ag^+(aq) + 2 NH3(aq) ⇌ Ag(NH3)2^+(aq)#

Step 1: Identify electron pair donor and acceptor

Ag^+ accepts an electron pair from two NH3 molecules to form the complex ion Ag(NH3)2^+. \( \mathrm{Ag}^{+} + 2 \mathrm{NH}_{3} \rightleftharpoons \mathrm{Ag}\left(\mathrm{NH}_{3}\right)_{2}^{+} \)

Step 2: Determine Lewis acid and base

Ag^+ is the Lewis acid as it accepts an electron pair from the NH3 molecules. NH3 is the Lewis base as it donates an electron pair to the Ag^+. #c. BF3(g) + F^-(aq) ⇌ BF4^-(aq)#

Step 1: Identify electron pair donor and acceptor

BF3 accepts an electron pair from F^- to form BF4^-. \( \mathrm{BF}_{3} + \mathrm{F}^{-} \rightleftharpoons \mathrm{BF}_{4}^{-} \)

Step 2: Determine Lewis acid and base

BF3 is the Lewis acid as it accepts an electron pair from the F^- ion. F^- is the Lewis base as it donates an electron pair to the BF3. In conclusion, for each reaction: a. B(OH)3 is the Lewis acid and H2O is the Lewis base. b. Ag^+ is the Lewis acid and NH3 is the Lewis base. c. BF3 is the Lewis acid and F^- is the Lewis base.