Question

Why is $N{H_4}OH$ a weak base when it has more concentration of $H$ ions than $OH$ ions $?$

Answer 1

First we have to know that the strength of base is depends on the value of ionization constant ($K$), that depends upon the equilibrium between ions and molecules that are not ionized in a solution. Hence the strength of bases depends on how much base ionizes in solution. A strong acid or base completely ionizes in solution.

Complete answer:
When concentration of hydrogen ions in the solution increases then the acidity of solution increases. As the concentration of hydroxide ions in the solution increases then the solution becomes more basic. Thus, as the hydrogen ion concentration increases hydroxide ion concentration falls in the solution.
$N{H_4}OH$ has higher ${H^ + }$ concentration than a stronger base. Ammonia is a typical weak base. Ammonia itself doesn’t contain hydroxide ions, but it reacts with water to produce hydroxide ions. Its chemical reaction is written as follows
$NH_3^ + + {H_2}O \rightleftharpoons NH_4^ + + OH$
Since $N{H_4}OH$ is partially ionised in water and produces a small amount of hydroxide ions (OH−).
Hence $N{H_4}OH$ is a weak base.

Note:
Base is said to be a strong base if it is $100\%$ ionized in solution. Whereas a base which is less than $100\%$ ionized in solution, known as weak base. Also note that, the salts with ions that are part of strong acids or bases will not hydrolyse, while salts with ions that are part of weak acids or bases will hydrolyse.