utilizes electrical energy to create chemical energy Electrolytic Cells utilizes electrical energy to create chemical energy

Electrolytic Cells electricity used to force non-spontaneous reactions to occur = endothermic electrolytic cells identified by presence of battery or power supply

Galvanic Cell Chemical Potential Energy Electrical Potential Energy Electrolytic Cell

Electrolytic Decomposition of H2O H2 produced at one electrode, O2 at other 2H2O + energy 2H2 + O2 Can you tell from the picture which electrode is producing H2? Which is producing O2?

Electrolytic cell works as the reverse of a galvanic cell this time: Zn is cathode; where reduced takes place & Cu is anode; where oxidation takes place

Two kinds of electrolytic cells Fused Salt Cells – used to purify metals (Fused means melted!) Electroplating Cells – designed to cover a surface with metal so will have specific properties

Electroplating Move desired coating from anode onto object to be plated Solution contains ions of element to be plated

Electroplating: Cu onto Al Al above Cu in Table J reaction will not happen spontaneously so… use external energy source (power supply or battery) to force reaction to occur

An Ox ate a Red Cat anode: electrode at which oxidation occurs cathode: electrode at which reduction occurs Electrode polarity opposite than galvanic cell! anode is positive cathode is negative

A POX on Electrolytic Cells Anode – Positive – Oxidation electrolytic cell: polarity determined by outside power supply anode attached to (+) terminal cathode attached to (-) terminal

(+) (-) (+) (-) Anode = Oxidation Cu  Cu+2 + 2e- Battery Cathode (Obj being Plated) = Reduction Cu+2 + 2e-  Cu (-) Cu+2 and SO4-2 Note: just moving Cu around

Plating cathode = object to be plated anode - made of metal want to plate on object solution: contains ions of plating metal Plating

purify metals from their ores Fused Salt Cells: used to Ox: 2Cl-1  Cl2 + 2e- Red: Na+1 + 1e-  Na

Why does NaCl have to be molten? Which electrode will Na+1 ions be attracted to? Which electrode will Cl-1 ions be attracted to?