Question

An acid is a substance that increases the concentration of H3O+ ions in solution. Look at the reaction below of phenol (C6H5OH) with water: Which reactant acts as an acid by contributing a H+ ion to create H3O+ in the chemical equation?

a.C6H5OH(aq)
b.H2O(l)
c.C6H5O–(aq)
d.H3O+(aq)

Answer 1

A. C6H5OH is the acid because, on the product side, it becomes C6H5O-. this means it lost a hydrogen, and this is what acids do they give hydrogen away.

Answer 2

Answer: Option (a) is the correct answer.

Step-by-step explanation:

The reaction will be as follows.

`C_(6)H_(5)OH(aq) + H_(2)O(l)`
`\rightarrow`
`H_(3)O^(+)(aq) + C_(6)H_(5)O^(-)(aq)`

Here, phenol is acting as an acid as it's conjugate base is more stabilized due to resonance. Whereas if
`H^(+)` ion is donated by water molecule then it will give a hydroxide ion which is not a strong base.

Therefore, here phenol is acting as an acid as it is donating an
`H^(+)` ion.