redox reactions. redox-oxidation states 16.2-16.3 day one
TRANSCRIPT
Redox Reactions
REDOX-OXIDATION STATES 16.2-16.3
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!!!
• Br2
• K+1
• LiF • CO2
• SO4-2
• Na2O2
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 H2O
- balance H by adding H+1
4. Add electrons to show lose or gain of charge5. Balance number of electrons6. Add together the two half reactions & verify
Al(s) + Ag+1 Al+3 + Ag(s)
Fe+2 + MnO4-1 Fe+3 + Mn+2
½ REACTIONS ACIDIC AND BASIC SOLN
Day Three
Balancing Redox Reactionsin 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 charge4. Balance number of electrons5. Add Water to balance O 6. Add H+1 to balance H
** NO DIFFERENCE THAN WHAT WE HAVE BEEN DOING!!!!!!!!!!!
HNO3 + H2S S + NO Acidic Solution
Balancing Redox Reactionsin 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 charge4. Balance number of electrons5. 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
NO2 NO-2 + NO3-1
Basic Soln