Bases: Acids:

ACIDS HCl(aq) → H+(aq) + Cl-(aq) Properties of Acids: Cause blue litmus paper to turn pink. Taste sour. Form H2(g) in front of active metals. ACIDS Produce H+ when dissolve in water. Form CO2(g) in front of carbonates. HCl(aq) → H+(aq) + Cl-(aq) (Arrhenius Model) (An acid donates H+,protons)

Cause phenolphthalein to turn red. Properties of Bases: Taste bitter & feel slippery. (Soap) Cause red litmus paper to turn blue. Bases Produce OH- when dissolve in water. Cause phenolphthalein to turn red. NaOH(s) → Na+(aq) + OH-(aq) (Arrhenius Model) (A base donates OH-)

Ion Product Constant for Water (Kw): H2O(l) H+(aq) + OH-(aq) neutral base acid x (1.0 x 10-7) (1.0 x 10-7) 1.0 x 10-14 Kw = [H+] [OH-] Kw=1.0 x 10-14

Example: If the H+ ion concentration of an aqueous solution is 1 x 10-5M. What is the OH- ion concentration? Is the solution acid, basic, or neutral? [H+] =1 x 10-5M Kw = [H+] [OH-] Kw = 1.0 x 10-14 [OH-] = [OH-] = ? [OH-] = 1.0 x 10-14 ÷ 1 x 10-5 [OH-] = 1.0 x 10-14 -(-5) = 1.0 x 10-14 +5 [OH-] = 1 x 10 -9 M (Makes sense?) The solution is acidic (Because [H+] > [OH-] )

The solution is neutral. Kw (10-14) = [H+] [OH-] Solution pH: acidic 10-3M > 10-11M basic 10-12M < 10-2M acidic 10-4M > 10-10M neutral 10-7M = 10-7M Conclusion: If [H+] > [OH-] The solution is acidic. If [H+] < [OH-] The solution is basic. If [H+] = [OH-] The solution is neutral.

The pH Scale:

The pH indicates the acidity level of a solution. pH Scale: 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 Acidic level increases Basic level increases Neutral solution

pH and pOH: pH: Is the negative logarithm of the [H+]. pH = - log [H+] (log XP = p log X) Example: pH= - log [H+] 1 [H+] =1 x 10-6 M = - log 10-6 = -(-6) log 10 = - (-6) = 6 pH= 6

The solution is neutral. If pH = 7 Kw (10-14) = [H+] [OH-] Solution pH: > acidic 3 10-3M 10-11M basic 12 10-12M < 10-2M acidic 4 10-4M > 10-10M neutral 7 = 10-7M 10-7M Conclusion: If pH < 7 The solution is acidic. The solution is basic. If pH > 7 The solution is neutral. If pH = 7

pH + pOH = 14 pH and pOH: pOH: Is the negative logarithm of the [OH]. pOH = - log [OH-] [H+] [OH-] = Kw 10-7 x 10-7 = 10-14 pH = -log 10-7 = -(-7) = 7 pOH = -log 10-7 = -(-7) = 7 7 + 7 = 14 pH + pOH = 14

Example: Calculate the pH and pOH of a solution in which [H+] = 1 x 10-4M. pH= - log [H+] [H+] =1 x 10-4 M = -log 10-4 pH = ? = - (-4) = 4 pOH = ? pH= 4 (acidic) pH + pOH = 14 4 + pOH = 14 pOH = 14 - 4 pOH = 10

10-pH [H+] = If pH= 8 [H+] = 10-4 M pH= 4 [H+] = 10-8 M pH= 8 pOH = 6

Complete the following table: [OH-] pH pOH acid base neutral 1x10-4 M 1x10-10 M x 4 10 1x10-6 M x 1x10-8 M 8 6 1x10-7 M 1x10-7 M 7 7 x 1x10-13 M 1x10-1 M x 13 1