1. Brønsted-Lowry Model Acids - proton (H + ) donors Bases – accepts proton (H + )

2. Brønsted-Lowry Model A Brønsted-Lowry acid is a proton donor A Brønsted-Lowry base is a proton acceptor Proton = Hydrogen ion = H +

3. The Brønsted definition means NH 3 is a BASE in water — and water is itself an ACID H+H+ H+H+ H+H+

4. Can you see how the HCl gives up a proton (H + ) to the H 2 O?

5. Acid donates the proton (H+), base accepts it. Which is the acid and which is the base in the forward reaction? CH 3 CO 2 H + H 2 O ⇌ H 3 O + + CH 3 CO 2 - CH 3 CO 2 H (acetic acid) – proton donor H 2 O (water = base) – proton acceptor

6. Brønsted-Lowry Model Amphoteric – something that can act as an acid or a base. Water is acting as both an acid and a base Base Acid Acid Base

7. Conjugate Pairs Base Pairs to Acid Acid Pairs to Base Conjugate Pairs NH 3, NH4 + H 2 O, OH -

8. What are the conjugate acid base pairs? HCl + H 2 O ⇌ H 3 O + + Cl - HCl (acid), Cl - (base) H 2 O (base), H 3 O + (acid)

9. Conjugate Pairs

10. Learning Check! Label the acid, base, conjugate acid, and conjugate base in each reaction: HCl + OH -  Cl - + H 2 O H 2 O + H 2 SO 4  HSO 4 - + H 3 O +