Question

In the chemical reaction H_3PO_4 + H_2O ↽−−⇀ H_3O^+ + H_2PO^−4, which of the above chemical species acts as a Brønsted-Lowry acid?

A. H_3PO_4
B. H_2O
C. H_3O^+
D. H_2PO^−4

Answer 1

In the given chemical reaction, H_3PO_4 donates a proton to H_2O, making H_3PO_4 the Brønsted-Lowry acid (option A) and H_2O the Brønsted-Lowry base.

Step-by-step explanation:

In the chemical equation H_3PO_4 + H_2O ⇋ H_3O^+ + H_2PO_4^-, the Brønsted-Lowry acid can be identified as the species that donates a proton (H+).

Phosphoric acid (H_3PO_4) donates a proton to water (H_2O), transforming into its conjugate base, H_2PO_4^- and forming hydronium ion (H_3O^+). Therefore, the Brønsted-Lowry acid in this reaction is H_3PO_4, which is option A. Water acts as the Brønsted-Lowry base as it accepts a proton. Neither H_2O, H_3O^+, nor H_2PO_4^- acts as an acid in this particular chemical equation.