electric cells
a simple electric cell
 a simple electric cell consists of two different metal
electrodes placed in an electrolyte
 metals high up in the reactivity series give up electrons
more readily; negative electrode in the cell
 metals low down in the reactivity series will be the positive
electrode in the cell
 voltage of electric cell depends
on the positions of the two
metals in the reactivity series;
the farther apart they are, the
higher the voltage
 use of electric cell: portable
energy such as batteries
portable energy: batteries
electric cells
a simple electric cell
 consists of pieces of Cu and Zn metals in a solution of NaCl
 zinc being more reactive than Cu is the negative electrode;
Cu metal is the positive electrode
zinc metal
(negative
electrode)
voltmeter
-
+
copper metal
(positive electrode)
NaCl(aq)
electric cells
a simple electric cell
 at the Zn electrode, Zn atoms give up electrons to form
Zn2+ ions
Zn(s)
Zn2+(aq) + 2e-
 at the Cu electrode, Cu2+ ions take in electrons to give Cu
atoms
Cu2+(aq) + 2e-
Cu(s)
 overall reaction
Zn(s) + Cu2+(aq)
Zn2+(aq) + Cu(s)
positive ions
are
form
cations
metals or H2
are
discharged at
are
produced at
an
example is
electroplating
cathode
gives
electrons to
battery
moving ions
is negative
electrode in
decomposes
electrolysis
takes
electrons from
anode
is
reactive metals
an example
is
are discharged
at
non-metals
anions
form
contains
ionic
compound
(molten/solution)
electrolyte
is positive
electrode in
are
produced at
Cr-plating
are
negative ions
copper
aluminium