Question

According to Bronsted and Lowry, which of the following is a base?
A.$C{H_3}CO{O^ - }$
B.$HCN$
C.$HOOCCOOH$
D.${C_6}{H_5}N{H_3}^ + $
E.$N{H_4}^ + $

Answer 1

Hint: Bronsted and Lowry devised the theory for the identification of acid and base among different solids and liquids or compounds. Now according to this theory what happens is that acid is that piece which will donate protons in the aqueous solution and base is a species which will accept protons in the aqueous solution.

Complete answer:
We already know that the boosted lowry acid will have the characteristic to donate or lose proton from itself. While bromated lowry will have the characteristic to accept protons from the outside of the compound.
The compounds given to us are $C{H_3}CO{O^ - }$, $HCN$, $HOOCCOOH$, ${C_6}{H_5}N{H_3}^ + $, $N{H_4}^ + $
We have to check for all these compounds,
Now in $HCN$ what happens is that when it is mixed in water the compound, the water molecule accepts the proton of the hydrogen ion and water acts as the Bronsted base while the compound $HCN$ acts as the Bronsted acid.
Similar thing happens for $HOOCCOOH$, it also loses a proton to water as it has two carboxylic groups which readily give hydrogen ions to the water molecule and it itself is stable due to resonance.
${C_6}{H_5}N{H_3}^ + $ and $N{H_4}^ + $ are both positive ions which on mixing in a water solution which readily give their positive ion to form their neutral compound and the water molecule accepts the hydrogen ion or the proton, therefore these are also Bronsted lowry acid.
Now in $C{H_3}CO{O^ - }$ what happens is that on mixing it in water it readily accepts the hydrogen and proton from the water molecule and therefore forms its neutral stable compound and as it is the one to accept the proton therefore, it is a bristled lowry acid.
Answer- $C{H_3}CO{O^ - }$ is a Bronsted lowry base.

Note:
Now in some cases there is some confusion that if a species donates hydroxide ion, then it is also a Bronsted lowry base but it is not so. The Bronsted lowry concept says that only the species having the capacity to accept the proton are Bronsted lowry bases.