Question

Classify each of the following reactants and products as an acid or base according to the Bronsted theory: H3PO4 + C6H5O- <=&gt; H2PO4- + C6H5OH
Which are acids and which are bases? Thanks!

Answer 1

Answer:

H₃PO₄ is an acid because donates the proton to fenolate.

Fenolate is the base because accepts the proton from the acid.

Explanation:

Bronsted theory mentioned that acid is the one that donates a proton to another compound and base is the one that receives it.

H₃PO₄   +   C₆H₅O⁻    ⇄      H₂PO₄⁻      +       C₆H₅OH

acid              base              conj. base            conj. acid

H₃PO₄ is an acid because donates the proton to fenolate.

Fenolate is the base because accepts the proton from the acid.

If we follow the dissociation, the diacid phosphate can donate two more protons, it is still a Bronsted acid, but it can act as an acid or a base. This is called amphoteric.