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Worksheet — Nernst Equation Under standard conditions, the cell potential, E°cer, is calculated from the standard potentials of the two half-reactions: £°cet = E° reduction half-reaction - &° oxidation half-reaction For a voltaic (spontaneous) cell, the cell potential must be positive. 4. Given the following half-reactions, decide which will remain as a reduction reaction and which will be reversed to become an oxidation reaction. Zn” (aq) + 2e > Zn(s) &°=-0.76V “\ceductioa or oxidation Al (aq) +3e > Al(s) = &°=- 1.66 V reduction oxidations Jmne ne sat Ur MALE re 2. Write out the overall reaction and calculate £°ceu. 5S nts DACH) > ZBtnls) + 24At*® 3. Which reaction will occur at the anode? _y ,-f2 Zep hls Att 4307 Which reaction will occur at the cathode? 4¢lerc&-» tn't 26° 2 gn a) label the solutions and electrodes in the diagram below. (put the oxidation half-reaction on the left) ¥ gnty ETS TAN a a) label the flow of electrons } b) label the flaw of anions in the salt bridge M* c) label the flow of cations in the salt bridge There is a standard notation for electrochemical cells. e the anode is drawn on the left and the cathode on the right. * phase changes are shown as vertical lines between components | e the salt bridge is shown as || s The outermost components must be solids Fill in the components for this pair of half-reactions. HOD MUM) Wnt OA) | eld Anode Cathode If there are no solids in a half-reaction, an inert electrode, such as Pt or even C(graphite) can be used. 
