This document discusses redox reactions and concepts related to oxidation states. It defines redox reactions as electron transfer reactions where oxidation and reduction occur simultaneously. It describes how oxidation states are assigned to atoms to indicate their relative oxidation or reduction levels. Common oxidizing and reducing agents are listed along with examples of species being oxidized or reduced. Disproportionation reactions are defined as redox reactions where an atom undergoes simultaneous oxidation and reduction, changing its oxidation state.

2. Oxidizing & Reducing Agents © my-chem-tutor.blogspot.com Oxidizing Agent - gains electrons - undergoes reduction - Oxidation state of atom decreases Reducing Agent - loses electrons - undergoes oxidation - Oxidation state of atom increases

3. © my-chem-tutor.blogspot.com H 2 O H 2 O 2 Fe 2+ Fe 3+ I - I 2 (aq) I 2 (aq) IO 3 - Cr 3+ Cr 2 O 7 2- MnO 2 (s) (in base) Mn 2+ (in acid) MnO 4 - Reduced Species Common Oxidizing Agents S 2 O 3 2- H 2 O H 2 O 2 Fe 3+ Fe 2+ I 2 (aq) I - NO 3 - NO 2 - O 2 (g) H 2 O 2 S 4 O 6 2- CO 2 (g) C 2 O 4 2- Oxidized Species Common Reducing Agents

4. Assigning Oxidation States © my-chem-tutor.blogspot.com (I) Elements (O 2 , P 4 , S 8 ) All atoms in an element have an O.S. of zero . (II) Ions (Na + , Mg 2+ , Zn 2+ ) O.S. = charge on ion. (III) Covalent molecules (H 2 O 2 , H 2 S, CH 4 ) Assume bond is ionic. e - in bond are assumed to reside on the more electronegative atom. (IV) Complex ions (SO 4 2- , NO 3 - ) - Sum of O.S. of elements = charge on ion - Notable exceptions: S 2 O 3 2- , S 4 O 6 2- , S 2 O 8 2-

5. © my-chem-tutor.blogspot.com O a = -2 O b = -1 S = +6 S a = +6 S b = -1 O = -2 S a = +6 S b = -2 O = -2