Question

Question #e7848

Answer 1

`NH_4^+` is the acid.
`OH^-` is the base
`NH_3` is the conjugate base
`H_2O` is the conjugate acid

Explanation:

The best way to figure out what's an acid or a base is to simply track the movement of your `H^+` ions.

• The species that donates an `H^+` ion is an `color(red)("acid")`.
• The species that recieves an `H^+` ion is a `color(blue)("base")`.

Notice that the `NH_4^+` ends up becoming `NH_3`, indicating the loss of one `H^+` ion. Similarly, `OH^-` becomes `H_2O`, indicating a gain of a `H^+` ion.

So, you can say that `NH_4^+` is the acid, and `OH^-` is the base.

Conjugates are basically the "other" term. For every acid, you have a conjugate base (that no longer has that extra `H^+` ion), and for every base, you have a conjugate acid (that has an extra `H^+` ion).

As mentioned above, `NH_4^+` ends up becoming `NH_3` post deprotonation (donation of the `H^+`) ion, so `NH_3` is your conjugate base. Similarly, `OH^-` becomes `H_2O` post protonation, so it is your conjugate acid.

Hope that helped :)