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Chemistry CHE 100 Notes
R. Acids and Bases

1. Arrhenius Definitions
   1. Acid: yields H¹⁺ in solution

   2. Base: yields OH^1- in solution

2. Dissociation
   1. HCl ----> H¹⁺ + Cl^1-

   2. H₂SO₄ ----> 2H¹⁺ + SO₄^2-

   3. HNO₃ ----> H¹⁺ + NO₃^1-

   4. HC₂H₃O₂ ----> H¹⁺ + C₂H₃O₂^1-

   5. NaOH ----> Na¹⁺ + OH^1-

   6. NaCl ----> Na¹⁺ + Cl^1-

3. Bronsted-Lowry Definition
   1. Acid: Proton Donor

   2. Base: Proton Acceptor

   3. Partial Dissociation
      1. First Dissociation: H₂CO₃ ----> H¹⁺ + HCO₃^1-

      2. Second Dissociation: HCO₃^1- ----> H¹⁺ + CO₃^2-

      3. What if: HCO₃^1- + H¹⁺ ----> H₂CO₃ ?

4. Properties of Acids and Bases

   Property	ACID	BASE
   Litmus	blue to red	red to blue
   Taste	sour	bitter
   Neutralize	base	acid
   Feel	N/A	soapy or slick

5. Titration
   1. Neutralization: H¹⁺ + OH^1- ----> H₂O

   2. Determine the concentration of an acid (or base) with a known base (or acid)

   3. Add a known concentration of an acid to an unknown concentration of a base until neutralization or an endpoint is reached

   4. Indicators
      1. Methyl Orange: pH 4 Red in acid: yellow in a base

      2. Methy Red: pH 5 Red in acid; Yellow in a base

      3. Phenolphthalein: at about pH 8.3 it is colorless: Red in a base

   5. Calculation
      1. (ml of known titrant) (N of known titrant) = (ml of sample) (N of sample)

      2. Therefore: millimole of known titrant = millimole of unknown sample

      3. N.B.: Rearranging equation to solve for unknown:
         (ml titrant) x (N titrant)/(ml sample) = (N sample)

6. Dissociation of Water
   1. HOH ----> H¹⁺ + OH^1-

   2. At 25^oC the product of the H¹⁺ and OH^1- concentrations is 1 x 10^-14 = K_w

   3. Kw at 25^oC = [H¹⁺] [OH^1-] = 1 x 10^-14

   4. Values in brackets mean concentration in Molarity = moles/liter

7. pH
   1. For neutral water [H¹⁺] = [OH^1-]

   2. Therefore the Square Root of 1 x 10^-14 = 1 x 10^-7 = [H¹⁺] = [OH^1-]

   3. pH = neg log of the H¹⁺ ion concentration = -log [H¹⁺]

   4. pOH = -log [OH^1-]

   5. N.B.: pH + pOH = 14 at 25^oC
      1. Acids
         1. pH acid: 0-7
         2. pOH acid: 14-7

      2. Bases
         1. pH base: 7-14
         2. pOH base: 7-0

   6. Example
      1. Give the pH of an acid when its concentration is [H¹⁺] = 1 x 10^-6 M

      2. pH = 6 and pOH = 8

   7. Example
      1. Give the pH of an acid when its concentration is [H¹⁺] = 1 x 10^-3 M

      2. pH = 3; The [OH^1-] = 1 x 10^-11 AND pOH = 11

   8. Example
      1. Give the pH of an acid when its concentration is [H¹⁺] = 3.00 x 10^-2

      2. Enter scientific notation 3.00 x 10^-2

      3. Press log and it should show -1.52

      4. Change the sign. Therefore the pH = 1.52 and the pOH = 12.48

8. Electrolytes
   1. Electrolytes: whose aqueous solutions conduct an electric current either strong or weak

   2. Nonelectrolytes: whose aqueous solutions do not conduct an electric current

9. Dissociation Equations
   1. Example: NaCl_(aq) ----> Na¹⁺_(aq) + Cl^1-_(aq)

   2. Example: NaOH_(aq) + HCl_(aq) ----> NaCl_(aq) + H₂O

   3. Then: Na¹⁺_(aq) + OH^1-_(aq) + H¹⁺_(aq) + Cl^1-_(aq) ----> Na¹⁺_(aq) + Cl^1-_(aq) + H₂O

   4. Finally: H¹⁺_(aq) + OH^1-_(aq) ----> H₂O

   5. Some Guidelines
      1. Write and balance equations in regular form

      2. Then change to ionic

      3. Molecular form to be kept

      4. Carefully express polyatomic ions

      5. Ions appearing on both sides of the equation can be crossed off

   6. Self Check
      1. Regular form: AgNO_3(aq) + NaCl_(aq)----> AgCl_(ppt) + NaNO_3(aq)

      2. Ionic:

      3. Then:

    
   

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