Unit 11: Acids and Bases Acids and Bases Models

Acids and Bases Acids Bases Tastes sour Turns litmus paper red Reacts with metal to form H2 Examples: Vinegar, Milk, Soda, Apples, Citrus Fruits Tastes bitter Turns litmus paper blue Feels slippery Examples: ammonia, lye, drain cleaner, baking soda

Acids and Bases ACIDIC SOLUTION: A solution that contains more hydrogen ions (H+, H3O+) than hydroxide ions. BASIC SOLUTION: A solution that contains more hydroxide ions (OH-) than hydrogen ions. WATER: is a neutral solution, meaning it contains the same amount of hydrogen ions as it does hydroxide ions.

Acid and Base Models Arrhenius Bronsted-Lowry Acids PRODUCE hydronium ions Bases PRODUCE hydroxide ions Acids are hydrogen DONORS Bases are hydrogen ion ACCEPTORS

Acids and Bases: Arrhenius Model Acids PRODUCE hydronium ions HCl  H+ + Cl- Bases PRODUCE hydroxide ions NaOH  Na+ + OH-

Acids and Bases: Bronsted-Lowry Model Acids are hydrogen DONORS Bases are hydrogen ion ACCEPTORS HCl + H2O  Cl- + H3O+ conjugate conjugate base acid

Determining the conjugates: The conjugate base is the compound from which the hydrogen was removed. It is formed from the acid. The conjugate acid is the compound to which the hydrogen is added. It is formed from the base.

Determining the conjugate acids and bases: 1. H2O + H2O ⇒ H3O+ + OH- 2. H2SO4 + OH- ⇒ HSO4- + H2O 3. HSO4- + H2O ⇒ SO4-2 + H3O+ 4. OH- + H3O+ ⇒ H2O + H2O 5. NH3 + H2O ⇒ NH4+ + OH-

Acids and Bases: Conjugate Acids and Bases Identifying Conjugate Acid and Bases

Strong Acids and Bases: Ionize completely in water (good conductors) Strong Acids: HCl, HNO3, H2SO4, HBr, HI, HClO4, HClO3 Strong Bases: LiOH, NaOH, KOH, RbOH, CsOH, Ca(OH)2, Ba(OH)2, Sr(OH)2

Weak Acids and Bases: Do not ionize completely in water (poor conductors) Weak Acids: HF, HC2H3O2, H3PO4, H2CO3, HCN Weak Bases: NH3

Acids and Bases Measurement Acid and Bases are measured on the pH scale which is derived from the concentration of hydrogen ions present in a solution Water is neutral because the concentration of hydrogen ions is equal to the concentration of hydroxide ions. H+ = 1.0 x 10-7 M OH- = 1.0 x 10 -7 M H+ = OH-

pH Scale:

Calculating pH: pH = -log[H+] pOH = -log[OH-] pH + pOH = 14

What is the pH and pOH of a 1 x 10-5M HCl solution? pH = -log(1 x 10-5) pH = 5 *Remember: pH + pOH = 14 So to calculate pOH: 14 – 5 = 9

Practice Problems What is the pH of 0.050M HNO3?

What is the pH of 1 x 10-3M NaOH?

Determine the pOH of a 735 L of a solution containing 0 Determine the pOH of a 735 L of a solution containing 0.340 moles of nitric acid.