• A?Br?nsted-Lowry acid?is a species that can donate a proton
• A?Br?nsted-Lowry base?is a species that can accept a proton
• In a reaction equilibrium the products are formed at the same rate as the reactants are used

CH₃COOH (aq) + H₂O (l) ????????? ???CH₃COO^-?(aq)? ? ? ? ? +? ? ? ? ?H₃O⁺?(aq)

acid? ? ? ? ? ? ? ? ?base?????????? ??? ?????conjugate base? ? ? ? ? ? ?conjugate acid

• The reactant CH₃COOH is linked to the product CH₃COO^-?by the transfer of a?proton?from the acid to the base
• Similarly, the H₂O molecule is linked to H₃O⁺?ion by the transfer of a proton
• These pairs are therefore called?conjugate acid-base pairs
• A?conjugate acid-base pair?is two species that are different from each other by a H⁺?ion
  • Conjugate?here means related
  • In other words, the acid and base are related to each other by one proton difference

• Species that can act both as proton donors and acceptors are called?amphiprotic
  • Eg. water as a Br?nsted-Lowry acid

The diagram shows water acting as a Br?nsted-Lowry acid by donating a proton to ammonia which accepts the proton using its lone pair of electrons

The Lewis diagram for the reaction of water with ammonia to show how water acts as a Br?nsted-Lowry acid and ammonia as a Br?nsted-Lowry base

• Eg. water as a Br?nsted-Lowry base

The diagram shows water acting as a Br?nsted-Lowry base by accepting a proton from hydrochloric acid proton using its lone pair of electrons

The Lewis diagram for the reaction of water with hydrochloric acid to show how water acts as a Br?nsted-Lowry base and ammonia as a Br?nsted-Lowry acid

What is the difference between amphiprotic and amphoteric?

• A compound that is?amphoteric?means it has both basic and acidic character
  • When the compound reacts with an acid, it shows that it has basic character
  • When it reacts with a base, it shows that it's acidic
  • An example of this is aluminum oxide which reacts with both hydrochloric acid and sodium hydroxide:

Al₂O₃?(s)+????6HCl?(aq)???→???2AlCl₃??(aq)???+?? 3H₂O (l)

Al₂O₃?(s)+???2NaOH?(aq)?+???3H₂O?(l)?????→???2NaAl(OH)₄?(aq)

• When a compound is?amphiprotic, it means it can act as a proton donor and as a proton acceptor
• Aluminium oxide is not amphiprotic, even though it is amphoteric

Amphiprotic versus Amphoteric Table

Answer

The correct option in?B

• • A conjugate acid-base pair differ only by an H⁺?ion