1. 10.2 Electrochemistry Objectives S2

2. Essential Questions
What is electricity and how does that relate to electrochemical cells?
What is an electrolytic cell?
What is a voltaic cell?
What is cell potential?
How do you calculate cell potential?

3. Movement of Electrons Redox RXN deal with movement of electrons
Can you think of something else where there is movement of electrons?
Movement of electrons and charge is the basis of ELECTRICITY

4. Electrochemical Cell
Devices that use Redox RXN to produce/use electricity
Cells that produce electricity are called voltaic
Like a battery
Cells that use electricity to drive RXN are electrolytic
Metal Plating
Electrolysis of water

5. e- → - Voltaic Cell Setup +
Use spontaneous Redox RXN to cause electron flow
e- → - +

6. Voltaic Cell Setup (cont)
21.1
Voltaic Cell Setup (cont)
In this voltaic cell, the electrons generated from the oxidation of Zn to Zn2+ flow through the external circuit (the wire) into the copper strip. These electrons reduce the surrounding Cu2+ to Cu. To maintain neutrality in the electrolytes, anions flow through the salt bridge

7. Voltaic Cell Setup (cont)
In this voltaic cell, the electrons generated from the oxidation of Zn to Zn2+ flow through the external circuit (the wire) into the copper strip. These electrons reduce the surrounding Cu2+ to Cu. To maintain neutrality in the electrolytes, anions flow through the salt bridge.

8. Voltaic Cell Setup (cont)
In this voltaic cell, the electrons generated from the oxidation of Zn to Zn2+ flow through the external circuit (the wire) into the copper strip. These electrons reduce the surrounding Cu2+ to Cu. To maintain neutrality in the electrolytes, anions flow through the salt bridge.

9. Voltaic Cell Setup (cont)
In this voltaic cell, the electrons generated from the oxidation of Zn to Zn2+ flow through the external circuit (the wire) into the copper strip. These electrons reduce the surrounding Cu2+ to Cu. To maintain neutrality in the electrolytes, anions flow through the salt bridge.

10. Voltaic Cell Setup (cont)
In this voltaic cell, the electrons generated from the oxidation of Zn to Zn2+ flow through the external circuit (the wire) into the copper strip. These electrons reduce the surrounding Cu2+ to Cu. To maintain neutrality in the electrolytes, anions flow through the salt bridge.

11. Electrochemical Cell Setup
Includes 2 electrodes in 2 Half Cells
Cathode-where reduction occurs (positive end of battery)
Anode- where oxidation occurs (negative end of battery)
Electrons are being given off at the anode and flow to the cathode
Includes Salt bridge connecting half cells and allow ions to flow back and forth

12. Cell Potentials E cell = E oxidation + E reduction
Driving force of the RXN and relates to energy released in RXN
Measured in Volts (V)
Cell potential is a combination of the oxidation potential and reduction potential
E cell = E oxidation + E reduction
If the standard cell potential is positive the reaction is spontaneous (occurs on its own)
If it is negative than it will not be spontaneous and will only occur when a current is applied

13. Cell Potentials (cont)
Standard Reduction Potentials listed on page p 674
Standard reduction potential can be used to find oxidation potentials by reversing the RXN and changing the sign
If you are given a RXN then the one being oxidized will have its sign reversed
If there is not reaction provided the smaller number gets reversed as oxidation

14. Determine Reduction potentials Ag1+/Ag E°= +0.80 V Al3+/Al E°= -1.66 V
Example: Calculate voltage of a cell composed of a silver electrode in Ag1+ solution with an Aluminum electrode in a Al3+ solution.
Determine Reduction potentials
Ag1+/Ag E°= V
Al3+/Al E°= V
Silver has a more positive potential so it will be reduced.
Since Aluminum is being oxidized we need to reverse the RXN and change the sign on the potential
E cell = = 2.46 V

15. Cell Potential (cont) Find the Ecell for the following reactions
2 Al + 3 I2 → 2 Al I-
Zn + Cu2+ → Zn2+ + Cu
Write half reactions, calculate Ecell, and draw the electrochemical cell
Ni Na → 2 Na+ + Ni
2 Li + 2 H+ → H2 + 2 Li+
Write half reactions, calculate Ecell, identify the anode and cathode, and write the overall reaction
Co2+/Co and Fe3+/Fe

16. Essential Questions
What is electricity and how does that relate to electrochemical cells?
What is a electrolytic cell?
What is a voltaic cell?
What is cell potential?
How do you calculate cell potential?

17. 10.2 Tracked Assignment
worksheet