Electrochemical Cells

Electrochemical Cells

Redox Reaction __________ metal is oxidized (gives up e-’s easily) while ____ ion is reduced (stronger ______ agent). Oxid: ________________ Red:_________________ Redox: _______________

What if we separated the Cu(s)/Cu2+ from the Zn(s)/Zn2+? NOTHING HAPPENS!!

There is NO way for the e-’s released by the oxidation of Zn metal to get over to the copper ions to reduce them to Cu metal

What if we provided a path for these electrons released by the oxidation of Zinc metal to get to the Copper ions in solution? Any bright ideas, Team?

Now the reaction would appear to be able to proceed… Problem!!

As the redox reaction proceeds we build up Zn2+ ions on the left. • On the right, we remove Cu2+ ions from solution • The anion concentration (ie. sulfate ion) does not change.･ • Thus, we are building up a net (+) chargein the zinc solution, and anet (-) charge in the copper solution･These charges will oppose the flow of e-’s. • We need a way to neutralize the charge build up in both solutions

Insert a salt bridge!! • Anions (SO42-) are going to the oxidation side • Cations (Zn+2) are going to the reduction side

The two solid metals in the different half-reactions are called electrodes • The electrode where oxidation is occurring is called theAnode • The electrode where reduction is occurring is called theCathode • The cathode is labeled "+"; "this electrode attracts e-’s" • The anode is labeled "-"; "this electrode repels e-’s”Open School

Electrochemical Cells