Redox Reactions

REDOX-OXIDATION STATES Day One

Oxidation-Reduction Process of gaining or losing electrons Oxidation: losing electrons Reduction: Gaining Electrons OIL RIG

How do we Identify if something is being reduced or oxidized? Oxidation States (Oxidation Numbers) – Computed for each element based on the number of electrons assigned There are FIVE (5) Rules for assigning Oxidation States

Oxidation State RULES 1.Oxidation state of an atom in a free element is ZERO (0). 2.Hydrogen always has an oxidation number of (+1), except in hydrides 3.Oxygen always has an oxidation number of (-2), except in peroxides

Oxidation State Rules 4. The sum of oxidation states of all atoms in: – Molecule = (0) – Ion = charge of the ion 5. In their compounds, – Group I metal = (+1) – Group II metals (+2)

LETS TRY A FEW!!! Br 2 K +1 LiF CO 2 SO 4 -2 Na 2 O 2

½ REACTIONS 16.4 Day Two

Balancing Redox Reactions 1.Assign Oxidation Numbers 2. Split reaction into two ½ reactions 3. Balance all elements except H and O - balance O by adding H 2 O - balance H by adding H Add electrons to show lose or gain of charge 5. Balance number of electrons 6. Add together the two half reactions & verify

Al(s) + Ag +1  Al +3 + Ag(s)

Fe +2 + MnO 4 -1  Fe +3 + Mn +2

½ REACTIONS ACIDIC AND BASIC SOLN Day Three

Balancing Redox Reactions in Acidic Solutions 1.Split reaction into two ½ reactions 2.Balance all elements except H and O 3.Add electrons to show lose or gain of charge 4.Balance number of electrons 5.Add Water to balance O 6.Add H +1 to balance H ** NO DIFFERENCE THAN WHAT WE HAVE BEEN DOING!!!!!!!!!!!

HNO 3 + H 2 S  S + NO Acidic Solution

Balancing Redox Reactions in Basic Solutions 1.Split reaction into two ½ reactions 2.Balance all elements except H and O 3.Add electrons to show lose or gain of charge 4.Balance number of electrons 5.Add Water to balance O 6.Add H +1 to balance H 7.Neutralize H +1 by adding the appropriate amount of OH -1 to EACH SIDE

NO 2  NO -2 + NO 3 -1 Basic Soln