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# What is the stronger base: ammonia or ethoxide ion?

Last updated date: 14th Jul 2024
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Hint :According to Arrhenius theory, bases ionize in water to yield hydroxide ions ($O{H^ - }$) . According to Brønsted-Lowry theory, base is any species that is capable of accepting a proton, which requires a lone pair of electrons to bond to the ${H^ + }$.

There is a relationship between the strength of an acid (or base) and the strength of its conjugate base (or conjugate acid) and that is
The stronger the acid, the weaker its conjugate base. The weaker the acid, the stronger its conjugate base.
The stronger the base, the weaker its conjugate acid. The weaker the base, the stronger its conjugate acid.
Now, ethanol is a weak acid
$C{H_3}C{H_2}OH + {H_{_2}}O \rightleftarrows C{H_3}C{H_{_2}}{O^ - } + {H_3}{O^ + }$ ${K_a} = 1 \times {10^{ - 16}}$
$C{H_3}C{H_{_2}}{O^ - }$ (ethoxide ion) is the conjugate base of $C{H_3}C{H_2}OH$(ethanol), which is the strong base.
$C{H_3}C{H_{_2}}{O^ - } + {H_3}{O^ + } \rightleftarrows C{H_3}C{H_2}OH + {H_{_2}}O$ In case of ammonia, it is a weak base
$N{H_3} + {H_2}O \rightleftarrows NH_4^ + + O{H^ - }$ ${K_b} = 1.8 \times {10^{ - 5}}$
Hence, it is clear from the above discussion of dissociation constant values that ethoxide ion is a stronger base than ammonia.

Ethoxide ion carries a negative charge and hence can easily accept ${H^ + }$ion. Whereas ammonia is a neutral molecule.
A strong base completely ionizes in water to give its conjugate acid and $O{H^ - }$ion.
The basic nature of the species is inversely proportional to the stability of the species. More the tendency of the base to accept ${H^ + }$ion, greater is its basic strength.