Acid and Base Strength

Acids Have a sour taste.

Acids Turn blue litmus red. Turn methyl orange red.

Acids Will react with: Mg + 2HCl  MgCl2 + H2 MgO + 2HCl  MgCl2 + H2O some metals to produce a salt and H2. metal oxides to produce a salt and H2O. metal carbonates to produce a salt, H2O, and CO2. bases to produce a salt and H2O. Mg + 2HCl  MgCl2 + H2 MgO + 2HCl  MgCl2 + H2O MgCO3 + 2HCl  MgCl2 + H2O + CO2 Mg(OH)2 + 2HCl  MgCl2 + 2H2O

Acids Are electrolytes. Conduct an electric current when dissolved.

Bases Have a bitter taste. Coffee itself is acidic, but it contains an alkaline compound – caffeine – which contributes to its bitter taste.

Bases Feel slimy or slippery to the touch.

Bases Turn red litmus blue. Turn methyl orange yellow. Turn phenolphthalein pink. Litmus pH scale.

Bases React with acids to produce salt and H2O. HCl + NaOH  NaCl + H2O

Bases Are electrolytes.

Review Properties of Acids Properties of Bases Taste sour. Turn litmus red. Proton (H+) donors. Inc. [H3O+] in aqueous solutions. Properties of Bases Taste bitter. Turn litmus blue. Proton acceptors. Inc. [OH-] in aqueous solutions. Review

Review pH Scale Traditionally 0 - 14. pH < 7  Acidic solution. Can have pH < 0 or > 14. pH < 7  Acidic solution. pH = 7  Neutral solution. pH > 7  Basic solution. Review

pH Scale 1 2 3 4 5 6 7 8 9 10 11 12 13 14 Acidic Basic pH Scale

HCl, A Strong Acid

HF, A Weak Acid

As [H+] Increases, [OH-1] Decreases 1x10-13 M 1x10-12 M 1x10-11 M 1x10-10 M 1x10-9 M 1x10-8 M 1x10-7 M 1x10-6 M 1x10-5 M 1x10-4 M 1x10-3 M 1x10-2 M 1x10-1 M 1x10-13 M 1x10-12 M 1x10-11 M 1x10-10 M 1x10-9 M 1x10-8 M 1x10-7 M 1x10-6 M 1x10-5 M 1x10-4 M 1x10-3 M 1x10-2 M 1x10-1 M Acid added to neutral solution Base added to neutral solution Neutral Solution [H+] [OH-1]

[H+] and [OH-1] in Water In any aqueous solution: [H+] [OH-1] = 1x10-14 As [H+] goes up, [OH-1] must decrease. As [OH-1] goes up, [H+] must decrease. In other words, adding an acid to water causes the solution to become more acidic and less basic. Adding a base to water causes the solution to become less acidic and more basic.

[H+] and [OH-1] in Water If [H+] = 1x10-3 M, what is [OH-1]? [H+][OH-1] = 1x10-14 (1x10-3 M)[OH-1] = 1x10-14 [OH-1] = (1x10-14) / (1x10-3) [OH-1] = 1x10-11 M If [OH-1] = 1x10-8 M, what is [H+]? [H+](1x10-8 M) = 1x10-14 [H+] = (1x10-14) / (1x10-8 M) [H+] = 1x10-6 M

pH pH = power of Hydrogen pH = -log10[H+] negative logarithmic (powers of ten) scale. pH = -log10[H+] If [H+] = 1x10-1 M, pH = -log(1x10-1 M) = 1 If [H+] = 1x10-2 M, pH = -log(1x10-2 M) = 2 If [H+] = 1x10-3 M, pH = -log(1x10-3 M) = 3

Calculations Involving pH, pOH, [H+], and [OH-] of strong Acids and Bases pH = -log [H+] pOH = -log [OH-] pOH + pH = 14  

[H3O+1] and [OH-1] [H3O+1] [OH-1]

pH and pOH What are the pH values of the following solutions? 1x10-1 M H+ pH = -log(1x10-1 M) = 1 1x10-3 M H+ pH = -log(1x10-3 M) = 3 1x10-5 M H+ pH = -log(1x10-5 M) = 5 1x10-1 M OH-1 [H+] = (1x10-14) / (1x10-1 M) = 1x10-13 M pH = -log(1x10-13 M) = 13