Cells and corrosion

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Cells and corrosion
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AN ACTIVITY SERIES FOR METALS
REF 353
With oxygen Li, Na, K, Ca and Ba react rapidly
at room temperature, while Mg, Al, Zn and Fe
react slowly (but burn vigorously if heated in
air or oxygen), and Sn, Pb and Cu react slowly
but only if they are heated. Li, Na, K, Ca and
Ba react with water (to form hydrogen gas) while
the other metals do not. With dilute acids Mg,
Al, Zn, Fe react readily, Pb and Sn react if the
acid is hot and Cu, Ag, Pt and Au do not react at
all. In displacement reactions Zn will displace
Fe, Cu and Ag from solutions of their cations but
will not displace Mg Fe will displace Cu and Ag
(but not Mg or Zn), while Cu will only displace Ag
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The activity series is a listing of metals in
order of decreasing reactivity, meaning
decreasing ease of oxidation or decreasing ease
of giving up electrons.
K Na Li Ba Ca Mg Al Zn Fe Sn Pb (H) Cu Ag Pt Au
This series can be used to decide whether a
metal will react with dilute acid (yes, if it is
to the left of hydrogen) whether a metal will
react with water (only if it is on the extreme
left) whether metal X will reduce the cation of
metal Y (yes, if X is to the left of Y) whether
metal P is a stronger reducing agent than metal Q
(yes, if P is to the left of Q) and conversely
whether metal L is a stronger oxidising agent
than metal M (yes, if L is to the right of M).
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REFER TO THIS LIST select three metals which
will displace a lead from a solution of lead
nitrate b iron from a solution of iron(II)
sulfate Write balanced equations for these
reactions.
K Na Li Ba Ca Mg Al Zn Fe Sn Pb (H) Cu Ag Pt Au
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CHEMICAL REACTIONS PRODUCING ELECTRICITY
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A strip of copper metal is suspended in a beaker
of copper sulphate solution, and a piece of zinc
in a beaker of zinc nitrate solution. The two
solutions are connected by a U-tube filled with a
solution of potassium nitrate held in place by
plugs of cotton wool (a strip of filter paper
soaked in ammonium nitrate is often used) This
U-tube which makes electrical contact between the
two solutions is called a salt bridge in order
to make electrical contact it must contain some
conducting substance such as a solution of
potassium nitrate.
CHEMICAL REACTIONS PRODUCING ELECTRICITY
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Copy
Blank electrochemical cell showing two half cells
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anode
cathode
-2e-
salt bridge
2e-
Zn2
Cu
Cu2
Zn
At this point we should move these labels
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-2e-
salt bridge
Zn
Cu
2e-
Cu2
Zn2
anode
cathode
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So what will happen here?
Mg
Ag
Ag
Mg2
Please refer to the previous example. What
electrical processes happen here. HINT Mg is the
anode!
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So what will happen here?
Mg
Ag
Ag
Mg2
some web links follow........
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