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BATTERIES

BATTERIES. What does a battery do?. Energy transformation: Chemical energy – stored in chemical compounds Electrical energy – moving charged particles (e-). History . Luigi Galvani – Italian physician studied frog anatomy

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BATTERIES

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  1. BATTERIES

  2. What does a battery do? • Energy transformation: • Chemical energy – stored in chemical compounds Electrical energy – moving charged particles (e-)

  3. History • Luigi Galvani – Italian physician studied frog anatomy • Brass hook held leg in place & other end touched iron railing. Leg twitched. • Believed the twitching of leg muscle due to “animal electricity” • Not true • simply demonstrated the electrical basis of nerve impulse

  4. The First Battery • Alessandro Volta – reproduced Galvani ‘s results • Due to chemical reaction between the two metals & saline in frog’s leg muscle • Tested hypothesis by layering salt-water-soaked paper layered between Zn & Ag • Connected wires & produced current • More layers – more current

  5. Electrochemical Cell • Device that transforms chemical energy into electrical energy • Electrodes – 2 different metals immersed in Electrolyte – substance that conducts electricity (salt water or acid) • Terminal - part of electrode above electrolyte, used to connect to circuit

  6. Chemical Reaction - Redox • Electrolyte reacts with each electrode • One electrode loses electrons & becomes (+) {oxidized} • Other gains electrons & becomes (-) {reduced} • Opposite charges – difference in potential energy - voltage - causes electrons to move from (+) anode to (-) cathode through circuit • Electrons move through the electrolyte from one electrode to other (negative electrode through electrolyte to positive electrode)

  7. BATTERY = several stacked electrochemical cells • Total voltage = all the individual cell voltages added together • Wet Cells – electrolyte Dry Cells – electrolyte is liquid – salt water is a paste (KOH or NaOH) or acid (car battery) (AAA, AA, C, D - alkaline)

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