Lewis definition Knowledge-Based Download PDF

Questions

1. 1.

   Which of the following statements correctly explains how the Lewis definition broadens the scope of acid–base chemistry beyond the Brønsted–Lowry definition?

   • A) It restricts acid–base chemistry exclusively to aqueous solutions where hydroxide ions are produced.
   • B) It encompasses reactions involving electron-pair sharing even when no proton transfer takes place.
   • C) It limits acid behavior strictly to species that possess a formal positive charge.
   • D) It requires an acid to transfer two or more protons simultaneously to a conjugate base.
2. 2.

   Which of the following processes represents an acid–base reaction under the Lewis definition but is not considered an acid–base reaction under the Brønsted–Lowry definition?

   • A) The formation of the tetrafluoroborate ion from boron trifluoride and a fluoride ion: $\text{BF}_3 + \text{F}^- \rightarrow \text{BF}_4^-$
   • B) The neutralization of hydrochloric acid with sodium hydroxide in aqueous solution: $\text{HCl} + \text{NaOH} \rightarrow \text{NaCl} + \text{H}_2\text{O}$
   • C) The ionization of acetic acid in water to yield hydronium and acetate ions: $\text{CH}_3\text{COOH} + \text{H}_2\text{O} \rightleftharpoons \text{H}_3\text{O}^+ + \text{CH}_3\text{COO}^-$
   • D) The reaction between gaseous ammonia and hydrogen chloride to form ammonium chloride: $\text{NH}_3 + \text{HCl} \rightarrow \text{NH}_4\text{Cl}$
3. 3.

   When a Lewis acid reacts with a Lewis base to form an adduct, what type of chemical bond is formed between the interacting species?

   • A) A coordinate covalent bond, in which both shared electrons originate from the Lewis base
   • B) An ionic bond, in which an electron is completely transferred from the Lewis acid to the Lewis base
   • C) A conventional covalent bond, in which each reacting atom supplies one electron to the shared pair
   • D) A hydrogen bond, in which a proton is transferred from the Lewis acid to the Lewis base
4. 4.

   According to the Lewis definition, what characterizes a Lewis base during an acid–base reaction?

   • A) It accepts an electron pair to complete its valence octet.
   • B) It donates a hydrogen ion to an accepting chemical species.
   • C) It donates an electron pair to form a coordinate covalent bond.
   • D) It accepts a proton to increase hydroxide ion concentration in water.
5. 5.

   Which of the following chemical species behaves as a Lewis acid by accepting an electron pair during an acid–base reaction?

   • A) $NH_3$
   • B) $OH^-$
   • C) $BF_3$
   • D) $F^-$