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Electrolysis

Pg. 658 - 660. Electrolysis. Let’s talk about the lab…. In lab the reactions were spontaneous! The solutions were arranged so that the electrons would move through the wires Voltaic cells involving spontaneous reactions are typically used to run motors and perform other useful work.

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Electrolysis

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  1. Pg. 658 - 660 Electrolysis

  2. Let’s talk about the lab… • In lab the reactions were spontaneous! • The solutions were arranged so that the electrons would move through the wires • Voltaic cells involving spontaneous reactions are typically used to run motors and perform other useful work

  3. Electrolysis • Some batteries can be recharged • What do YOU have to do in order to recharge a battery?

  4. Overall (cell) reaction 2H2O(l) H2(g) + O2(g) Oxidation half-reaction 2H2O(l) 4H+(aq)+ O2(g) + 4e- Reduction half-reaction 2H2O(l) + 4e- 2H2(g) + 2OH-(aq) Electrolysis • Forces a current through a cell to produce a change that would otherwise not occur • Example: Electrolysis of Water

  5. What is Electroplating? • Electroplating:electrical energy from a battery (or other substance) provides electrons to convert metal ions into solid metal atoms • The result: • Deposits a thin layer of metal on another surface • This can protect the surface OR improve the surface’s appearance • Ex: Coating a “cheap” jewelry with a thin layer of silver or gold

  6. Sn Fe + - Sn2+ How do we accomplish electroplating? • An electroplating cell consists of: • Two electrodes (anode and cathode) • An appropriate solution of ions • A source of electricity Sn Sn2+ + 2e- Sn2+ + 2e-  Sn

  7. Why do you need to know this? • Tomorrow YOU will be electroplating a paper clip • That’s right! You are going to coat a paper clip with another metal  the wonders of chemistry NEVER cease! :o)

  8. Glavanic Cells 2 cells 2 solutions Saltbridge Anode/oxidation e- flow anode  cathode oxid.  red Eletroplating 1 cell 1 solution Battery Anode/oxidation e- flow anode  cathode oxid.  red Electrochemical Cells Comparison

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