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Warmup 4/15/14

Warmup 4/15/14. What do you know about batteries? Tell me. Objective Tonight’s Homework. To learn how we define an electrochemical cell. none. Notes on Electrochemical Cells. Yesterday, we talked about how you can use electricity to break down chemicals in a cell.

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Warmup 4/15/14

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  1. Warmup4/15/14 What do you know about batteries? Tell me Objective Tonight’s Homework To learn how we define an electrochemical cell none

  2. Notes on Electrochemical Cells Yesterday, we talked about how you can use electricity to break down chemicals in a cell. Today we’re going to talk about the reverse – how you can use the voltage difference between the cathode and anode to generate electric current.

  3. Notes on Electrochemical Cells We’ve essentially seen this before. Electrons flow from the cathode to the anode to reacha lower enthalpy. However, we can add a few things now. For one, we canmeasure a voltage at theanode and cathode. The difference between the two tells us how much “pressure” electrons have to flow through the solution. Given different materials and solutions, we can get different voltages. e-

  4. Notes on Electrochemical Cells But there’s more. As electronsbuild up on the anode, we canuse them. Many of the electrons will be“pushed” to flow through thewire that connects cathodeand anode. When these electrons returnto the cathode, they won’tattach to the metal. Instead,they’ll just stay there, building up. Eventually, they’ll build up to the point where they no longer want to flow from the anode. e-

  5. Notes on Electrochemical Cells However, while they’re flowing,we can use them. If we attach a device thatuses electricity to the wire, wecan use those flowing electronsto do useful work. This is how we get electricalenergy and this is how abattery you buy in a store works. e-

  6. Notes on Electrochemical Cells At rightis a diagramof a simple“dry cell”battery. (get thisdiagramdown)

  7. Notes on Electrochemical Cells Contrast thisto a carbattery, whichuses multiplecells bathedin sulfuric acidas theirelectrolytesolution. (get a roughsketch of this,too)

  8. Notes on Electrochemical Cells In a rechargeable battery, electricity is applied to force the electrons to go back the other way, restoring the voltage difference. However, after many uses, the solution will eventually break down or react with other components, making it so the battery can no longer be recharged.

  9. Practice on Electrochemical Cells Pp 679: 34, 35, 37

  10. Exit Question #43 Why do you think hooking multiple batteries together gives more voltage? a) You can’t link batteries together. If you try, they explode. b) Because the electrons coming out of one battery push them harder out the next. c) It doesn’t give more voltage. It gives more current. d) Because the chemicals combine, making it stronger. e) No one knows. f) None of the above

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