Name ________________________________________________
Period ________
Redox in Action: Voltaic cells: (How is a battery Like a waterfall?)
Two Reactions:
Cu(s) + ZnSO4(aq)  Zn(s) + CuSO4(aq)
Zn(s) + CuSO4(aq)  Cu(s) + ZnSO4(aq
Oxidation: ____________________
Reduction: ____________________________
During this reaction the Zn and CuSO4 decreases, While the Cu metal and ZnSO4 increases.
(Reactants ________________, Products ___________________!)
Zn + CuSO4  Cu + ZnSO4
Oxidation: _______________
Reduction: ___________________
Salt Bridge – allows flow of spectator_________ in ______________ direction of
_____________ to flow to maintain _______________
Practice:
1. Draw arrows in the diagram to show direction of electron flow, and the ion flow
2. Write the half reactions for the oxidation and reduction which occurs.
3. Label the anode and cathode
4. What happens to the mass of the Cu electrode? ___________. The mass of the Al electrode?___________
Electrochemistry / electrochemical cells
Voltaic cells:
___________________Redox reactions
__________________: energy is released during a chemical change
Chemical energy  ______________ energy
Electrolytic cells: “splitting with electricity”
Electrolytic cell (electrolysis of Fused sodium chloride)
NaCl(l)  Na0(s) + Cl20(g)
Battery _______ electrons oxidizing _____ions to ________ at the _______
Battery _____ electrons to the ___________, reducing _____ ions to _____
Oxidation:
Reduction:
Practice
The diagram at left represents a cell for the electrolysis of fused Al2O3
2Al2O3(l)  4Al (s) + 3O2(g
1. What ion will be attracted to the anode?
The cathode?
2. Write the balanced half reaction that occurs at the anode.
3. Which electrode will increase in mass? Why?
Electrolytic cells: “splitting with electricity”
______spontaneous Redox reaction
______________ – outside energy drives a chemical change
Electrical energy  _____________ energy
Electroplating (an application of electrolytic cells)
Practice
The diagram represents a cell for electroplating silver.
1. Is this cell a voltaic or electrolytic cell? __________
Why?
2. Which object is the cathode? _________
3. Write the half reaction that occurs at the cathode.
4. What happens to the concentration of Ag+(aq) while the cell operates?