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chemistry paper 1
chemistry - energy changes
chemistry - chemical and fuel cells
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Cards (9)
Cell
Composed of
two electrodes
dipped in an
electrolyte
solution. It produces electricity from a chemical reaction.
Battery
Consists of
two
or
more cells connected in series
Voltage obtained from a
cell
Determined by the
identities
of
metals
used as electrodes and the identity and concentration of an electrolyte
Advantages and disadvantages of using cells and batteries
Advantages: more or less cheap, some are
rechargeable
, a
convenient
source of electrical energy
Disadvantages:
harmful
chemicals
Rechargeable cells
Chemical reactions are
reversed
when an
external
current is
supplied
Non-rechargeable cells
Reactants are
used
up, cannot be
recharged
Fuel cell
Supplied by
fuel
and
oxygen
to
oxidise
the fuel to generate electricity
Overall reaction in a hydrogen fuel cell
1. Cathode: 2 H2 → 4 H+ + 4 e−
2. Anode: O2 + 4 H+ + 4 e−→ 2 H2O
3. Overall: 2 H2 + O2 → 2 H2O
Advantages and disadvantages of hydrogen fuel cells
Advantages: no
pollutants
, no
recharging
Disadvantages:
flammable
, H2 difficult to store, fossil fuel production,
toxic
chemicals,
expensive
production of H2 by electrolysis