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Making Electricity.

Making Electricity. A cell is an apparatus which generates electricity from a chemical reaction. A Battery is when two or more cells are joined together. There are in general, two main types of cell i.e. Wet and Dry Cells . In a dry cell the liquid of the wet cell is replaced by a paste.

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Making Electricity.

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  1. Making Electricity. • A cell is an apparatus which generates electricity from a chemical reaction. • A Battery is when two or more cells are joined together. • There are in general, two main types of cell i.e. Wet and Dry Cells. In a dry cell the liquid of the wet cell is replaced by a paste. • We more commonly use dry cells since they don’t leak. • Some cells can be Recharged. The Lead/acid cell is a rechargeable cell.

  2. Chemical Reactions in cells • To make a cell all we require is two different metals and an Electrolyte. Zn metal is Oxidised and Cu2+ions are Reduced Electrons flow from the more active metal to the least active metal Cu/Cu2+ Zn/Zn2+ Salt or Ion Bridge.(To complete the circuit)

  3. Other types of Voltaic Cell No Ion Bridge required here as ions can move freely through the solution. In each case: Zn= Zn2++ 2e (Oxidation) and Cu2++2e=Cu (Reduction)= As with all three representations of the Voltaic Cell the Electrons flow from the More Active metal to the Least Active Metal.The Further the metals are apart in Electrochemical Series, the bigger the reading on the Voltmeter.

  4. We can also get a flow of electrons between twonon-metals. Here the Sulphite ions are oxidised to Sulphate ions as they Reduce Bromine molecules to bromideions.ie The electrons flow from the solution that is Oxidised to the one that is Reduced. Br2(aq) SO32-/SO42-aq Half- Equations: SO32- +H2O = SO42-+2H++2e Br2 + 2e = 2Br- In Half-Equations the electrons go on the right-hand side if the species is being Oxidised and on the left if it is Reduced

  5. The Electrochemical Series • Potassium • Sodium • Calcium • Magnesium • Aluminium • Zinc • Iron • Nickel • Tin • Lead • Hydrogen • Copper • Mercury • Silver • Gold • Platinum A Displacement Reaction will occur if a Metal higher up in the ElectrochemicalSeries is added to an Ionic solution which contains Metal Ions of a Metal lower down in the Electrochemical Series.

  6. Imagine Magnesium is added to a Copper Sulphate Solution Mg2+SO2-4(aq) + Cu(s) • Mg(s) + Cu2+SO2-4(aq) Ion-Electron Half –Equations: Spectator Ion (doesn’t change charge). Mg(s) Mg2+(aq) + 2e (Oxidation) Cu2+(aq) + 2e Cu(s) (Reduction) Cu2+ + Mg Mg2+ + Cu (Redox or Ionic equation) The blue colour will eventually disappear as all the Copper Ions are used up Copper Sulphate + Mg Brown Copper metal is seen at the bottom of the beaker

  7. OILRIG Oxidation is Loss of Electrons Reduction is Gain of Electrons

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