Transcript Comparison of a Button Cell to a Dry Cell - slider-chemistry-12

Comparison of a Button Cell to a
Dry Cell
By Elisha, Jeremy and Tom
Button Cell
Chemistry of the Button Cell
• Half Equations
▫ Cathode reaction
Ag2O (s) + H2O (l) + 2e- → 2Ag (s) + 2OH▫ Anode Reaction
Zn (s) + 2OH- → ZnO (s) + H2O + 2e-
• Full Equation
Zn (s) + Ag2O (s) → 2Ag (s) + ZnO (s)
Cost and Practicality
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Silver is an expensive metal
The production of the cell is therefore expensive
Non rechargeable
Small and light
Has a relatively long life span
Impact on Society
• Due to its small size it has allowed the
production of small electrical appliances
• Due to its non toxic nature it has allowed for it to
be used inside the body
Environmental Impacts
• Due to its unrechargeable nature, it has to be
discarded or recycled after only one use
• Potassium hydroxide that is found within the
cell is caustic (causing corrosion)
• No highly toxic materials that will harm the
environment
Dry Cell/ Alkaline Cell
Chemistry
• Half Equations
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▫ Cathode reaction▫ MnO2(s) + 2H20(l) +2e  Mn(OH)2 (s)+2OH (aq)
▫ Anode Reaction
Zn(s)+2OH (aq)  Zn (OH)2 (s) + 2e
▫ Overall Reaction
▫ MnO2(s) + 2H20(l) + Zn(s)+2OH(aq)Mn(OH)2
(s)+2OH (aq)+Zn (OH)2 (s)
Cost and Practicality
• Very cheap
• Form of paste it is very convenient , being very
transportable.
• Small and easy to store and use
• Maintains a steady voltage, therefore they are good for a
range of electronic such as torches, walkman and toys.
• Cannot be recharged
• Short life
• Cannot deliver a high current
• Battery may leak
Impact on Society
• Due to its low constant voltage it is used for
common appliances such as torches, toys and
portable radios/cds
• Due to its mobility , portable items like
flashlights could be used , therefore increasing
the development of electrial equipments/
devices.
• The popularity of batteries have increased
Environmental Impact
• Small amounts of zinc are not problematic,
however large amounts of zinc is a threat.
• Manganese is also a heavy metal, dispose in
large quantities are not beneficial for the
environment.