Question

Which of the following can act as both Bronsted acid and Bronsted base?
A.\[O_2^ \oplus \]
B.HCl
C.\[HSO_4^ - \]
D.\[N{a_2}C{O_3}\]

Answer 1

Hint:Two scientists named J. N. Bronsted and T. M. Lowry worked independently on classifying acids and bases based on the ability of the compounds to accept electrons or donate electrons. Their work was later combined to give the Bronsted – Lowry theory.

Complete Step-by-Step Answer:
Before we move forward with the solution of the given question, let us first understand some important basic concepts.
According to The Bronsted - Lowry theory, the chemical species which donated electrons were identified as Bronsted bases, while the chemical species which accepted electrons were identified as Bronsted bases. The give and take of electrons took place between different species takes place to attain a stable electronic configuration.
Another way of looking at acids and bases is by the property of either accepting or donating protons or \[{H^ + }\] . The species which accept \[{H^ + }\] are known as Bronsted base while the species which releases \[{H^ + }\] are known as Bronsted acids.
Let us now discuss the given compounds:
A. \[O_2^ \oplus \] : \[O_2^ \oplus \] is incapable of either donating or accepting protons because of its positive charge.
B.HCl: HCl can donate protons but cannot accept any protons. Hence, HCl is a Bronsted acid
C. \[HSO_4^ - \] : \[HSO_4^ - \] can accept a proton to form sulphuric acid as well as it can donate a proton to form sulphate ion. Hence \[HSO_4^ - \] acts as both Bronsted acid and Bronsted Base.
D. \[N{a_2}C{O_3}\] : \[N{a_2}C{O_3}\] can only accept a proton but cannot donate an \[{H^ + }\] ion. Hence, it is a Bronsted Base.

Hence, Option C is the correct option

Note: The atoms which have their valence shells filled at less than half their valence shell capacity tend to accept electrons, because this way the electronegative character keeps on increasing. The electronegative character of a chemical species is directly proportional to its acidic character. Similarly, as the electronegativity of a species decreases, the tendency for that species to donate electrons increases. Hence, Electronegativity is inversely proportional to the basicity of the species.