L2 : Acid & Bases - Acid Base Salts, Science, Class 7 Video Lecture

hello friends this video on acids bases
and salts part 2 is brought to you by
exam for your calm no more fear from
exam so let us now see what our assets
now the word acid is derived from a
Latin word but a seal which means SAR
now does that imply that acids are those
substances which are sorry and taste
well to some extent so these acids the
tastes are so let's take some examples
which we have already tasted like lemons
and oranges we all who have tasted it
and we all know that they are scientists
and they are acidic because they contain
an acid called the citric acid let us
take another example vinegar so we all
would have tasted vinegar if not raw
vinegar but at least in some food items
like chow mein or mature Ian so these
kind of food items they use vinegar so
vinegar is again silent taste and
vinegar contains an acid called acetic
acid
let's take yet another example let's
take one very common example our body
what is it made of
what is our body made up of our body
contains a lot of proteins like and what
are proteins made up of proteins are
made up of amino acids so what is it
acid again
so proteins are also made up of acids so
you see proteins they play such an
important role they a help to in the
construction of our entire body and they
are also made up of some acids so these
proteins they also contain the amino
acids think of the process of digestion
so in one of our previous lessons we
spoke about the process of digestion how
do the food that we eat get broken down
into sink
forms and then absorbed by our body to
provide this energy so during this
process of digestion
do you remember what happens in the
stomach the stomach contains
hydrochloric acid HCL and this
hydrochloric acid plays a very important
role in the stomach because due to this
acidic medium the enzyme pepsin becomes
active and pepsin helps in the digestion
of proteins in the stomach so HCl plays
a very important role in the stomach so
here also you see acids are there so you
keep it inside our body also we see so
many acids present here there now when
the concentration of this HCl increases
in the stomach that is when we suffer
from acidity so so that's the that's how
the Oracle problem of acidity comes up
so you take example of spinach spinach
also contains an acid called the
obsolete acid you take example of code
which is consumed by us very frequently
and curd is actually prepared from milk
so this card also contain an acid called
the lactic acid so all these common
substances and things will go to acids
so yes it is really important to know
what and acids now the correct I would
not say that the correct way of defining
acid is that is why it's taste because
it is not possible to taste all types of
acids because some acids might be
extremely harmful being consumed so
therefore we cannot consume it
now if the only way we are defining acid
is by their taste then we will not be
able to find out a lot of acids so this
is basically one characteristic of
assets that they are serve in taste but
yes there are other properties of acids
which we are going to discuss now by
which we can actually distinguish which
is an acid and which
oh please so let's see what our basis so
these are the substances which are
mostly bitter in taste so let's look at
a few examples now not only bitter they
all they are also kind of soapy in touch
so I am sure you would have understood
some of the examples like the soap
itself soap is definitely going to be
scorpion Tex oils like when you put soap
it on your palms what happens it is like
kind of slippery it's like kind of slimy
so that kind of touch is referred to
when we say soapy in touch so some other
examples are bleach the washing soda or
baking soda they are also bases so if
you are ever were to chance to taste
baking soda because I will not advise
you to taste and so for the bleach of
course do not do that so we are actually
going to talk about how to distinguish
which is a base and which is an acid so
there is absolutely no need to taste
these substances the exam just now I
gave you an example like that when the
concentration of hydrochloric acid in
the stomach increases that causes
acidity and when you have acidity you
feel being in the stomach you feel
uneasiness discomfort and how do you get
rid of that with the help of antacid
tablets
so these antacid tablets they are
actually basic in nature so when these
have tablets are consumed they reach the
stomach and they reduce the acidity so
now antacids are bases so bases and
acids they are like just opposite so
they neutralize the effect of each other
so bases will neutralize or it will
bring down the acidity of the stomach
and that is how you feel better after
taking the antacid tablets
now these bases in the initial days they
were also known as the alkaline so acids
and alkaline where the terms which were
used those days so alkaline is basically
an Arabic word which means ashes of the
saltwater saltwater is nothing but
plant which mostly grows in the soil
grow in the salt marshes so ashes of
that plant was referred to as alkaline
so that was the earlier name of basis
but later it was more commonly called as
base so now the question is is it
necessary that all substances have to be
either acidic or basic
can there be substances which are
neither basic nor acid it yes of course
there can be so these kind of substances
which are need a basic nor acidic in
nature they are said to be neutral so
they are it's like they are neither
positive nor negative so they are
neutral so they are like a common man so
some of the examples of neutral
substances are sugar salt water these
are all examples of neutral substances
so now in this lesson we are going to
focus mostly on acids and bases and we
are going to see how can we distinguish
between an acid and the base how can we
determine a particular substance is an
acid or a base thank you please visit
www.canadianoutback.com
thank you once again