Question

All of the following reactions are examples of the Lewis definition of acid-base behavior except

a. Ni + 4 CO → Ni(CO)4
b. Ag+ + 2 NH3 → [Ag(NH3)2]+
c. BF3 + NH3 → H3NBF3
d. Cl- + AlCl3 → AlCl4-
e. Zn + 2 H+ → Zn2+ + H2

Answer 1

Reaction Zn + 2H+ ⇒ Zn2+ + H2 is not the example of lewis definition of acid base behavior.

Step-by-step explanation:

In the Lewis theory of acid-base reactions, bases donate pairs of electrons and acids accept pairs of electrons.

A Lewis acid is therefore any substance, such as the H+ ion, that can accept a pair of nonbonding electrons. A Lewis base is any substance, such as the OH- ion, that can donate a pair of nonbonding electrons.

Therefore,

a) In Ni + 4 CO → Ni(CO)4

Nickel act as lewis acid (Transition metals such as titanium, iron and nickel may have up to eighteen electrons and can frequently accept electron pairs from Lewis bases) and CO act as lewis base because it has lone pair.

b) In Ag+ + 2 NH3 → [Ag(NH3)2]+

Ammonia act as lewis base due to presence of lone pair and Ag+ act as lewis acid due to deficiency of electron

c) In BF3 + NH3 → H3NBF3

BF3 act as lewis acid due to deficiency of electron and Ammonia act as lewis base due to presence of lone pair.

d ) In Cl- + AlCl3 → AlCl4-

AlCl3 act as lewis acid due to deficiency of electron and Cl- act as lewis base due to excess of electron.

e) In Zn + 2 H+ → Zn2+ + H2

H+ is lewis acid but Zn cannot act as lewis base.

Answer 2

e . Zn + 2 H+ → Zn2 + H2

Step-by-step explanation:

• lewis acid base reactions are defined as the sharing of electrons between acid and base without change in oxidation state of any atom participating in the reaction.
• in (a) we have a pair of electrons donated by CO to vacant orbitals of Ni but there is no change in the oxidation states of any element.
• similarly in (b),(c),(d) electrons are shared between acid and base without change in the oxidation state of any element.
• but, in (e), we have the oxidation state of Zn changed from 0 to +2 and the oxidation state of H is changed from +1 to 0.
• so,(e) is not the example of lewis definition of acid-base behaviour.