## conjugate acids/bases

Aashka Popat 1A
Posts: 50
Joined: Sat Sep 07, 2019 12:16 am

### conjugate acids/bases

What exactly are conjugate acids and bases, and how would you write the formula for a compound's conjugate acids?

Ashley Fang 2G
Posts: 102
Joined: Fri Aug 30, 2019 12:17 am

### Re: conjugate acids/bases

A conjugate acid is a base with a hydrogen ion added to it.
A conjugate base is what is left over after an acid has donated a proton during a chemical reaction.

Posts: 49
Joined: Wed Sep 18, 2019 12:20 am

### Re: conjugate acids/bases

Let's look at an example:

HBr + H2O --> H3O+ + Br-

Here, HBr is the acid and H2O acts as the base. H3O+ is the conjugate acid as it is the species that is protonated, and Br- is the conjugate base because it is the species from which a proton is donated. The formula for the conjugate base of HBr is Br-, because the conjugate base of an acid has one fewer H+ ion than the acid. The formula for the conjugate acid of H2O is H3O+, because the conjugate acid of a base has one more H+ ion than the base.

Chantel_2I
Posts: 109
Joined: Sat Sep 07, 2019 12:19 am

### Re: conjugate acids/bases

You can write the formula for conjugate acids and bases by adding the original compound to water, and then showing that the reaction yields OH- and the conjugate acid or H+ and the conjugate base.
For acid dissociation:
A + H2O -> A- + H30+
A- is the conjugate base

For base dissociation:
B + H2O -> BH + -OH
BH is the conjugate acid

nickianel_4b
Posts: 50
Joined: Thu Jul 25, 2019 12:17 am

### Re: conjugate acids/bases

HA + B --> A- + BH
which is the same thing as
parent acid+parent base-->conjugate base+conjugate acid

As you can see the parent acid donates its H+ and becomes a conjugate base. The parent base accepts the H+ and becomes a conjugate acid.