Brønsted-Lowry Acids & Bases (College Board AP® Chemistry): Study Guide
Brønsted-Lowry Acids & Bases
The Brønsted-Lowry theory defines acids and bases in terms of proton transfer
A Brønsted-Lowry acid donates a proton (H+)
A Brønsted-Lowry base receive a proton (H+)
The Brønsted-Lowry theory is not limited to the aqueous state, therefore, the principle can be applied to reactions in the gas phase
Brønsted-Lowry acid reacting with a Brønsted-Lowry base
The Brønsted-Lowry acid donates a proton to the Brønsted-Lowry base that accepts a proton
Worked Example
Identify the Brønsted-Lowry acid and the Brønsted-Lowry base in the following chemical reaction
H2SO4(aq) + H2O(l) → HSO4−(aq) + H3O+(aq)
| Brønsted-Lowry acid | Brønsted-Lowry base |
(A) | H2SO4 | H3O+ |
(B) | H2SO4 | H2O |
(C) | H2O | H3O+ |
(D) | H2O | H2SO4 |
Answer:
The correct option is B
H2SO4 donate a proton to H2O
So, H2SO4 must be the Brønsted-Lowry acid and H2O the Brønsted-Lowry base
Water as a Brønsted-Lowry Acid & Base
A lot of acid-base reactions occur in aqueous state
Water can act both as a Brønsted-Lowry acid and Brønsted-Lowry base
Species that can donate or receive protons are called amphiprotic
Water as a Brønsted-Lowry acid
Diagram showing how water acts as Brønsted-Lowry acid
Water as a Brønsted-Lowry acid donates one proton to ammonia
Lewis structure for the reaction between water and ammonia
Lewis structures that show the reaction between water and ammonia, and the charges they acquire when they become ions
Water as a Brønsted-Lowry base
Diagram showing how water acts as Brønsted-Lowry base
Water as a Brønsted-Lowry base receives a proton from the hydrochloric acid
Lewis structure for the reaction between water and hydrochloric acid
Lewis structures that show the reaction between water and hydrochloric acid, and the charges they acquire when they become ions
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