Day 2: Balancing Redox Reactions in Acidic or Basic solutions

Review Redox Balancing: Steps: Write half rxn’s Balance atoms Balance electrons Add the half rxn’s Review Redox Balancing: Balance the following chemical equation using the half reaction method Easy: __Fe(s) + __Ag+  __Fe+3 + __Ag(s) Hard: __NH3 + __O2  __NO + __H2O

Balancing Redox Rxns in Acid/Alkaline Solution Some redox rxns occur in solutions that are acidic or basic, so H2O, H+ , and OH- are also involved in the reactions For acid soln Steps: Write half rxn’s Balance atoms Balance electrons Add the half rxn’s 2a. Add H2O to balance the O’s 2b. Add H+ to balance the H’s 2c. Add OH- to both sides of the rxn for each H used For base soln

Example: The following reaction takes place in an acidic solution. Balance it. VO2+1 (aq) + Zn(s)  VO2+ (aq) + Zn2+ (aq)

Example: The following reaction takes place in a basic solution. Balance it. Al(s) + S(s)  Al(OH)3(s) + HS- (aq)

Steps: Write half rxn’s Balance atoms Balance electrons Add the half rxn’s