Unit 10: Acids and Bases

Arrhenius

Acid: Produces H ( H₃​O) in water.

• HCl + H₂O→ H₃O + Cl

Base: Produces OH in water.

• NaOH → Na + OH

Bronsted–Lowry

Acid: Donates a proton (H+)

Base: Accepts a proton

Acidic Solution

[H] > [OH]

• pH is low

Basic Solution

[H] < [OH]

• pH is high

Neutral Solution

@25*C [H] = [OH]

K_w

H₂O + H₂O → H₃O + OH

• K_w is the constant for ionization of water

• K_w always equals to 1 × 10^-14 at 25*C

pH

A measure of how acidic a solution i

• pH = -log[H]

→ Smaller pH: more acidic

Dissociation

When an ionic compound dissociates into ions

Ionization

When a molecular compound forms ions by reacting with water

Strong acids/bases

Fully dissociate into their ions

• K_a is big → lots of products consisting of ions

Weak acids/bases

Partially dissociate into their ions

• K_a is small → product remains

Determining pH of a strong acid/base

1. Write balanced chemical equation

2. Use stoichiometry to find [H] or [OH]

3. Find the pH → -log[H]

Determining pH of a weak acid/base

1. Create an ICE table

2. You’re given K so we can solve for x → very small K so we can ingore

3. Solve for [H]

4. Find the pH=-log[H]