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Cells & Batteries

Cells & Batteries. Our bodies use a small electrical signal to control our hearts . Some people have a problem with their heart not beating properly. Electricity used to operate a pacemaker comes from an electrochemical cell that supplies a steady current. Pacemaker. Lithium & Iodine.

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Cells & Batteries

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  1. Cells & Batteries

  2. Our bodies use a small electrical signal to control our hearts. • Some people have a problem with their heart not beating properly. • Electricity used to operate a pacemaker comes from an electrochemical cell that supplies a steady current. Pacemaker

  3. Lithium & Iodine • An electrochemical cell is a package of chemicals designed to produce small amounts of electricity. • The electricity the cell produces comes from chemical reactions. • Other cells, made with other chemicals, are used in things like toys, cars & computers.

  4. Electrolyte • Paste or liquid that conducts electricity because it contains chemicals that form ions. • Ion: an atom or a group of atoms that has become chemically charged.

  5. 2 Main types of cells: Dry Cells Wet Cells Uses a liquid electrolyte that is usually an acid (sulfuric acid). Many of the earliest cells were wet cells. Used in vehicles • Chemicals are in a paste; sealed. • Chemicals don’t leak out • Used in flashlights

  6. 2 Main types of cells: Dry Cells Wet Cells Cheaper and easier to make Dangerous; liquid electrolyte can spill and is highly corrosive.

  7. Wet Cells

  8. Solutions? • Problems? Heavy & Rigid

  9. Plastic • Normally an insulator, but substances can be added to make it act like a metal. • Not yet as powerful as metal-based cells. • Light & Flexible- can be as thin as a credit card.

  10. Primary Cells

  11. Secondary Cells • Also called rechargeable cells • Chemical reactions can be reversed by using an external electrical source to run electricity back through the cell. • Reverse reaction must occur efficiently-Nickel Oxide & cadmium- Advertised as Ni-Cad batteries

  12. Not Perfect Even rechargeable cells wear out in time.

  13. Batteries • Connect cells together.

  14. Alessandro Volta made the first usable battery around 1800 • Humphry Davy connected 2000 cells together to form one battery in 1807.

  15. Work of scientists let to a whole new field: Electrochemistry

  16. Electrochemistry • Study of chemical reactions involving electricity.

  17. Electrolysis • Process which splits water into hydrogen and oxygen.

  18. Electroplating • Coating a cheaper metal with a think layer of gold or silver. • Less expensive & stronger. Gold plating

  19. Anodizing • Coating aluminum parts with a layer of aluminum oxide. • Coating is much harder than just aluminum. • Used in products such as screen doors, airplane or car parts, kitchenware, and jewelry.

  20. Electrorefining • Removes impurities from metal (like gold). • Automobile companies also use electrochemistry to bond special paints onto car parts.

  21. Check & Reflect • Page 294, #s 1-8

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