STRENGTHS OF ACIDS AND BASES ELECTRICAL CONDUCTIVITY Acidic

STRENGTHS OF ACIDS AND BASES

ELECTRICAL CONDUCTIVITY Acidic and basic solutions conduct electricity. We can see a current being conducting by electrocuting a pickle. A pickle has been soaked with a solution of vinegar and salt. (ions are from the acid and Na+ and Cl) The ions are able to carry the current. What color do you think the light emitted will be? Why would it be that color? You tube-electrocuting a pickle

STRENGTHS OF ACIDS Acids that completely ionize (dissociate) are called strong acids. Strong acids produce a strong electric current = strong electrolyte HCl(aq) +H 2 O(l) H 3 O+(aq) + Cl-(aq) (notice there is a one way arrow meaning it completely ionizes and does not reform HCl)

STRENGTHS OF ACIDS Weak acids partially ionize in solutions = weak electrolyte Produce fewer ions and cannot conduct electricity as efficiently as strong acids HC 2 H 3 O 2(aq) +H 2 O(l) H 3 O+(aq) + C 2 H 3 O 2 -(aq) (notice there is a two way arrow meaning it partially ionizes and does reform HC 2 H 3 O 2)

SIX STRONG ACIDS Hydrochloric acid: HCl 2. Hydrobromic acid: HBr 3. Hydroiodic acid: HI 4. Sulfuric acid: H 2 SO 4 5. Nitric acid: HNO 3 6. Perchloric acid: HCl. O 4 These acids completely dissociate in water. 1.

EIGHT STRONG BASES 1. 2. 3. 4. 5. 6. 7. 8. Lithium hydroxide: Li. OH Sodium hydroxide: Na. OH Potassium hydroxide: KOH Rubidium hydroxide: Rb. OH Cesium hydroxide: Cs. OH Calcium hydroxide: Ca(OH)2 Strontium hydroxide: Sr(OH)2 Barium hydroxide: Ba(OH)2 These bases completely dissociate in water.

ACID/BASE STRENGTH VS. CONCENTRATION Do not get acid/base strength confused with concentration. Acid/base strength is based on the ability to dissociate. Concentration is based on how much is dissolved in solution. You can have a strong dilute acid – the acid completely dissociates, but there is not much acid dissolved in solution

ACID IONIZATION CONSTANT Acid ionization constant (Ka) is the value of the equilibrium constant expression(Keq) for the ionization of a weak acid. Large Ka strong acid (much greater than 1) Small Ka weak acid (much less than 1)

BASE IONIZATION CONSTANT The base ionization constant (Kb) is the value of the equilibrium constant expression (Keq) for the ionization of a base Large Kb strong base (much greater than 1) Small Kb weak base (much less than 1)

WRITE THE IONIZATION EQUATION AND ACID IONIZATION CONSTANT (KA) EXPRESSIONS FOR THE ACID HF If you calculate Ka, it will be a weak acid so it will have a double arrow. Add it to water. HF(aq) + H 2 O(l) H 3 O+(aq) + F- (aq) (A) (B) (CA) (CB) Keq = Ka = [H 3 O+] [F -] [HF] Leave out liquids and solids in Keq But keep products over reactants

WRITE THE IONIZATION EQUATION AND BASE IONIZATION CONSTANT (KB) EXPRESSIONS FOR THE BASE NH 3 If you calculate Kb, it will be a weak base so it will have a double arrow. Add it to water. NH 3(aq) + H 2 O(l) NH 4+ (aq) + OH- (aq) (B) (A) (CB) Keq = Kb = [NH 4 +] [OH-] [NH 3] Leave out liquids and solids in Keq But keep products over reactants