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Electrochemical cells

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Primary and Secondary Cells Yes write the following down in your notes... Electrochemical Cells There are two types of Electrochemical cells 1)Primary (disposable) 2 ... – PowerPoint PPT presentation

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Title: Electrochemical cells


1
Electrochemical cells
  • Primary and Secondary Cells

2
Electrochemical cells
  • Yes write the following down in your notes...
  • Electrochemical Cells
  • There are two types of Electrochemical cells
  • 1)Primary (disposable)
  • 2) Secondary (rechargeable)
  • In secondary cells two reactions can occur, one
    discharges the cell and another occurs when the
    cell is recharged

3
Primary cells(write in notes)
  • In a primary cell, chemical reactions use up some
    of the materials in the cell as electrons flow
    from the cell
  • When the materials have been used up the cell is
    said to be discharged and can not be recharged
  • There are two basic types of primary cells
  • The primary wet cell and...
  • The primary dry cell

4
Primary wet cell(Do not take notes)
  • The wet cell, also known as a voltaic cell, was
    invented in 1800 by Volta

5
Voltaic cell(Do Not take notes)
  • The voltaic cell is called a wet cell because it
    is made of two pieces of metal (e.g. magnesium
    and copper) that are placed in a liquid (e.g.
    hydrochloric acid)
  • The metal pieces are called electrodes, while the
    liquid is called an electrolyte
  • The magnesium electrode reacts with the acid, and
    the energy released separates electrons from the
    magnesium atoms. These electrons collect on the
    magnesium electrode (negative terminal)

6
Voltaic cell(Do Not take notes)
  • At the same time, positive charges collect on the
    copper plate (the positive terminal)
  • Current only flows when connected to a circuit
  • Disadvantages
  • Danger of spilling electrolyte(acid)
  • Continual need to replace zinc plate and
    acid(consumed)

7
The wet cell(voltaic cell)(Take notes)
  • The wet cell(voltaic cell)
  • Consists of two metal electrodes (magnesium and
    copper) placed in a solution known as an
    electrolyte (usually an acid, e.g. HCl)
  • The magnesium (Mg) reacts with the acid releasing
    energy that separates the electrons from the
    magnesium atoms (the negative terminal)
  • Positive charges build up on the copper (the
    positive terminal)

8
The wet cell(voltaic cell)(Take notes)
  • The chemical reaction and build up of electrons
    give the electrons energy
  • For every electron that leaves the negative
    terminal of the circuit, another electron must
    move out of the circuit and onto the positive
    terminal
  • Electrons release their energy (voltage) to the
    load

9
(No Transcript)
10
Dry Cells (Take notes)
  • The electrolyte in dry cells is not a liquid as
    in wet cells but rather a paste so dry cells are
    not exactly dry

11
Secondary Cells (take notes)
  • Secondary cells are also known as rechargeable
    batteries and have a second recharging chemical
    reaction in addition to the discharging reaction
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