Extraction of Metals at the Top of the Activity Series Video Lecture - Class 10

right so let us come to the extraction
of metals high in the reactivity series
like sodium calcium magnesium no these
these metals are higher in the
reactivity series so they have a
different method of extraction because
what happens is that what we used to do
in metals medium in the reactivity
series is that we used to take an oxide
like zinc oxide and we used to reduce it
with carbon and then we used to get zinc
and carbon monoxide so we used to take
the oxide of the metal take carbon and
we used to reduce it with carbon to get
the pure metal and carbon monoxide but
in case of these metals what happens is
that if you take suppose calcium oxide
and you reduce it with carbon no
reaction will take place because calcium
and other metals like sodium and
magnesium they have more affinity for
oxygen than carbon so calcium actually
likes to stay with oxygen rather than
staying with carbon it does not like
carbon like in in case of zinc it like
carbon more than oxygen
it had more affinity for carbon than
oxygen but in this case
calcium is happy with oxygen and it does
not want to react to it carbon so that
carbon can displace oxygen so this
reaction does not take place so we we
need a different method for extracting
such metals and that is electrolysis now
in electrolysis what we do is that we
have a container and we have two plates
the plates can be of anything in this
case and it is connected to a battery
this is the symbol for a battery this is
the negative terminal and this is the
positive terminal so
the battery over here this is the
positive terminal so the plate connected
to this terminal will naturally acquire
a positive charge and the plate
connected to the negative terminal will
acquire a negative charge and what we do
is that we dip these plates in a
solution and this solution is that of
the metal chloride or it may be oxide so
it's a it's basically a metal ionic
compound of that metal so what happens
is that the metal in and this is in
liquid form so in liquid form the ionic
salt will obviously dissociate into ions
like if we have sodium chloride let us
take sodium chloride in the molten form
it will form na+ and cl- ions this is
this is the molten form not the solid
form and not even the occurs for the
molten form so we have any plus and Cl
minus so they are independently existing
in the solution so what will happen is
that this ne plus let me make it a
little bit clearer
this is a necklace this ne+ will get
attracted to this negatively charged
plate and it will get deposited over
here and the cl- will get attracted to
this positive charge plate and will get
deposited over here so what will happen
that when any Plus will get deposited on
this negatively charged plate it will
take an electron from the plate and it
will form sodium metal and for this
reason this plate is made up of sodium
metal only so that from the solution
more and more sodium metal gets
deposited on the plate and we get more
and more metal pure metal and over here
in the positively charged plate the
chlorine chlorine minus iron when
released its electron and it will become
chlorine gas so this is basically what
happens now
this plate which is negatively charged
is called the cathode and the plate
which is positively charged is called
the unknown now there will be a lot of
confusion regarding which one is cathode
and which one is unknown so a simple way
to determine this is that a node starts
with an E and addition also starts with
an E so I know it should be positive
which is the symbol of addition just
remember this that an old addition so
positive and then automatically the
cathode will become negative but the
thing is that this ne plus ion moves
towards the cathode so this ne plus ion
is called a cation and the CL minus ions
moves towards the anode so the CL minus
ion is called an anion so in general
what actually happens is that
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