Sedimentation and Decantation - Separation of Substances, Science, Class 6 Video Lecture

hello friends this video on separation
of substances part 7 is brought to you
by exam for calm
no more fear from exam or many more
processes so the next process that we
are going to talk about this
sedimentation so sedimentation the word
sedimentation has come from the word
sediment so something which you know
kind of settles down and comes to the
bottom that is sediment so it is a
separation technique for insoluble
particles from water under the influence
of gravity so now there are certain
particles which do not dissolve in water
so let us see certain examples let's say
when you mix sugar with water and you
stir it properly what happens sugar
completely dissolves in water so you do
not get to see the particles of sugar
inside water but if instead of sugar if
you try to mix and in water and if used
no matter how much ever you still you
can still see the sand particles because
then it doesn't dissolve in water so
sand is insoluble in water now let us
say if you take some sand put it in
water steer it completely so let's say
something like this so even if you keep
stirring it completely so everywhere you
have sand particles but the moment you
stop stirring and if you leave it
undisturbed for some time so after some
time what do you see you see that all
the sand particles they tend to settle
down at the bottom and this settlement
at the bottom is termed as sediment and
this is called sedimentation so
basically using which time under the
influence of gravity the heavier
particles of sand particles are heavier
than water that is why they gradually
came and settled down at the bottom of
the water so that means you see now the
topmost layer of water is like water
mostly free from the sand particles and
the bottom most layer contains the sand
so that's how you see the segregation
has happened so you can separate sand
from water so with this technique now
this technique comes a groups out to be
very useful to separate mixture of
particles which are of identical sizes
so let us say if you have to separate if
you have a mixture of sand and sugar so
so size-wise they are more or less same
so you cannot use sieving to separate
them so what you can do is you put that
mixture inside water and stir it
properly so what will happen all the
sugar particles will get dissolved in
water and all the sand particles they
will settle down at the bottom so that's
how you can separate so because this
sugar will remain dissolved in water and
the sand will come down at the bottom so
that's how you can remove the sand from
that mixture so that that's one way so
here in this process what you get you
get clear water at the top and the sand
or muddy water towards the bottom now
the question is how do we finally
separated it so then next step is
another process which is called
decantation so in the animation what we
do is we remove a layer of liquid and
that's how we separate the sedimentation
is always followed by decantation so let
us say let me take this example so let's
say you have two different liquids which
are which do not mix with each other
let's say oil and water so if you think
a glass put some water put some oil try
to mix them they will never get rich
together and what you will see that oil
being lighter than water like in case of
the previous example sand particles
behavior so they came down at the bottom
now oil is lighter so the oil will float
on water so oil remains at the top so
two separate layers have been formed one
layer of oil another layer of water so
now what you can do is you can just
remove the layer from this Bank so from
this container so what you do is you
take another container just for the top
layer of oil into that other container
so now what you have active decantation
is done so in one container you have oil
and in the other container
you have water so that's how you could
separate two liquids but this would be
possible only if the liquids are even
miscible immiscible that means they do
not mix with each other because if the
liquids makes meet each other in that
case you will not be able to get such
distinct layers like so this is how this
is one example of decapitations
another example of decantation could
also be separating invisible liquids as
one instance the other instance could be
two separate insoluble particles from
fluids the same example so which we do
for sedimentation so if you have multi
water or water mixed with sand particles
you leave it for some time so the sand
particles being heavier they will settle
down at the bottom so this process of
sedimentation so by sedimentation you
just want that distinct layers but in
order to actually separate it it has to
be followed by the decant patient that
is the clean water needs to be poured
into some other containers and all you
have clean water here and only sand left
over here in this containers so
sedimentation is always followed by
decantation now the liquid which women
which we pour into some other vessel it
is not necessary that liquid will always
be the good one or it will always be the
desire ticket for example in this is
clean water is the desired thing and
that is being poured into the other
vessel but in this example maybe the oil
is some bad oil some dirty oil so that
is not the desired substance so it
depends so decantation is all about just
separating two components of a mixture
so if you talk about purpose of the
camtasia it could be to remove unwanted
components for example let's say you
have some unwanted oil or some harmful
oil spilled over a glass of water so you
want to remove that oil so that that is
the purpose may be to remove unwanted
substances or the or another example
be let's say when you prepare pulses so
before you prep replace part preparing
in the garlic the first thing that you
do is you use wash the pulses with water
now why do you wash it with water
because when you pour water in a bowl
containing pulses all the unwanted
components may be husks or any other
thing they start floating on the surface
of water as soon as you pour water into
the bowl and keep it for some time
you'll see some fuzz cause our seed
coverings they tend to float on the
surface of water and then you just throw
that water away so all that unwanted
components are also thrown away so that
is how we wash rallies or pulses before
we cook them so that's an example of
decantation see if you want you can just
try it out at your home so in fact you
can ask your mom and she will tell you
that before preparing rice before
preparing that this is what she does she
she cleans the pulses she cleans their
eyes with water and the purpose of
cleaning is this so when she put some
water on that rice all the lightning
particles will be present within the
rice grains they came to float on water
and then that topmost layer of water has
been thrown away and that's how you are
also getting rid of those unwanted
components so my purpose of the
plantation could be to remove harmful
substances to remove undesirable
components the other purpose could also
be to get the desired component for
example when you have muddy water so you
wanted clean water from muddy water so
basically the liquid that you get here
is the clean water which is the desired
component right so here what you get is
the undesired component which you want
to be thrown and here what you get is
the desired component so the purpose can
be two ways so one purpose would be to
remove unwanted things the other purpose
could be to get the desired thing so it
depends upon the mixture which we are
dealing with so this is the process of
decantation city condition is all about
they are removing a layer of one
component from the other so let us now
look at the advantages and disadvantages
of decantation so when it comes to
decantation it is very effect
in separating in soluble solids or
liquids for example oil and water which
are insoluble liquids mud and water
which are in which is like an insoluble
solid so these kind of mixtures their
separation is done very effectively
using recantation but when it comes to
the neatness of the process so it is not
very effective in separating the
components of a mixture completely so
completely is the most important term
here so what do I mean by that so let's
say then when I give you the example of
mud water to dealing water so that clean
water which we get is just by pouring
that upper layers of water so there are
chances that there might be some traces
of mud or sand particles in that peeling
water also because this process is not
very effective because it is just that
there are a width times the sand
particles are going down and then from
the same vessel itself we are pouring
down the upper part of the water so
there are chances definitely that some
small amount of mud or sand particles
might be there so therefore this process
is not completely foolproof so the water
that you get by decantation from mud
water that water is not pure enough that
you can directly drink it so that means
this process is not a foolproof process
of separation so what do we do to bring
upon an improvement to it thank you
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