Chapter 10 Acids and Bases DE Chemistry – King William High School Chapter 10 Acids and Bases

1. Acids & Bases Acids start with H Bases end with -OH Acid nomenclature (table 10.1 on p.324) binary  hydro….ic acid ternary  “ate” becomes “ic” “ite” becomes “ous”

Bronsted-Lowry Bronsted-Lowry acid = proton (H+) donor Bronsted-Lowry base = proton acceptor EX: HCl + H2O  H3O+ + Cl- EX: NH3 + H2O  NH4+ + OH-

Conjugate acid-base pairs EX: HCl + H2O  H3O+ + Cl- EX: NH3 + H2O  NH4+ + OH-

2. Strengths of Acids & Bases Strong acids = strong electrolytes Weak acids = weak electrolytes Review table 10.3 on p. 329 – list of strong and weak acids Strong bases = strong electrolytes Weak bases = weak electrolytes Review p. 331 for a list a strong bases

3. Acid- Base Equilibrium LeChatelier’s principle – when equilibrium is disturbed…the rates of the forward and reverse reactions change to reestablish equilbrium EX: HF + H2O  F- + H3O+ add HF? remove HF? add F-?

4. Ionization of water Kw = [H3O+][OH-] = [1 x 10-7 M][1 x 10-7 M] EX: A vinegar solution has a hydroxide concentration of 5.0 x 10-12 M at 25oC. What is the hydronium concentration? Is the solution acidic or basic?

5. pH scale Below 7 = acid…above 7 = base  pH = -log [H+] = -log[H3O+] EX: Calculate the pH of an aspirin solution if it has a hydronium concentration of 1.7 x 10-3 M.

Calculating [H3O+] from pH EX: Determine the [H3O+] for solutions having the following pH values: a. pH = 3.0 b. pH = 8.25

6. Acid-Base reactions Acids react with metals (single replacement) to produce hydrogen gas (K, Na, Ca, Mg, Al, Zn, Fe, Sn) When acids react with carbonates or bicarbonates they produce CO2, water and a salt

Neutralization reactions When acids and bases react they form water and a salt EX: hydrochloric acid & potassium hydroxide

Acid-Base titration Neutralizing an acid sample with a known amount of base Convert mL of base to L  convert to moles of base using molarity  convert to moles of acid (stoichiometry)  calculate acid molarity EX: a 25 mL sample of HCl is placed in a flask with a few drops of indicator. If 32.6 mL of a 0.185 M NaOH solution is needed to reach the endpoint…what is the molarity of the acid?

7. Buffers Maintain pH by neutralizing small amounts of acid or base Buffers in blood to maintain a pH around 7.4 Weak acids and their conjugate base salt make good buffers EX: Which are good buffers? HCl (a strong acid) and NaCl? H3PO4? HF (a weak acid) and NaF?