hello I am Dr. Aizaz from MedicoVisual.com
you know that acidity or
basicity of a solution is determined by concentration of free protons inside it
or concentration of hydrogen ion inside it this solution among these is most
acidic because it has highest concentration of hydrogen ion inside it
while this one is least acidic similar to that this solution is most basic because
it has least concentration of hydrogen ion inside it and this one is least
basic because of highest amount of hydrogen ion concentration inside it now
this way of representing the strength of an acid or base in terms of hydrogen ion
concentration isn't an efficient method because it involves lots of zeros
*BEFORE* the point so imagine your friend in laboratory saying that hey I just
created a solution with hydrogen ion concentration of zero point zero zero
zero zero one the equivalent per liter I hate mentioning these lots of zeros
even I forgot that actual number of zeros involved in this so there must be
some solution to this problem well one way is that we can write it down in
terms of powers of 10 we can write the hydrogen ion concentration of solution
in powers of 10 as 10 raise to power minus 1 10 raised to power minus 4 and
so on but even that isn't an efficient way so well there is something called
logarithm or log in mathematics. now what is log. simply put
that if X is 10 raise to power y then log of X would be simply Y I know you
are confused so let me explain you with a simple example
this value "thousand", it can be written as 10 x 10 x 10 or 10 multiplied
by itself three times or 10 raised to power 3 so log of this value "thousand"
is simply 3 so we eliminate this 10 and it's simply written as 3 log of
thousand is simply 3. another example. 10,000 which is 10 multiplied by
itself 4 times a 10 raise to power 4 log of 10,000 is simply 4. The 1 unit
change in logarithmic form of a value is equal to 10 times change in that value. now
logarithmic form has been changed from 3 to 4 but the value has increased from
thousand to ten thousand so value has increased by 10 times another 10 is
multiplied here. Another example of log
0.0001 is also written as 10 raised to power minus 4. log of this value 10
raised to power minus 4 is simply minus 4. Now we can write it down
write down the logarithmic form of hydrogen ion concentration like
this that this solution has a minus 1 minus 4 minus 7 and so on but this poses
another problem if we take log of hydrogen ion concentration because
hydrogen ion concentration is a small value so minus signs are involved in
this so we hate mentioning those minus signs
here so what we do is that we take up this equation and we multiply it by
minus sign at both side so this will become negative log so negative log of
0.0001 is 4 now this is the equation which we love so we can write it down
here that negative log hydrogen ion concentration for this
solution is one this is 4, this is seven. so what we see is that negative sign is
removed. So this is the equation this negative log of hydrogen ion
concentration is called pH or power of hydrogen and we can represent the
acidity or basicity of a solution simply in terms of power of hydrogen now our
friend is very happy now he can simply say that he just created a solution with
pH of 8 rather than mentioning lots of zeros. Water is a neutral substance one
mole of water it dissociates into equal number of hydroxide ion and protons
free proton that is it dissociates into 10 raised to power minus 7 moles of
hydroxide ion and 10 raised to power minus 7 moles of protons so it's a
neutral substance because hydroxide anion and concentration of hydroxide ion
and free proton is equal now if we take negative log of hydrogen ion
concentration of water it would become 7 so 7 is considered as a neutral pH
solutions having pH less than 7 are considered acidic because they have
larger number, they have more concentration of free protons and
substances the solutions having pH more than 7 are considered basic so further
away the pH further away from 7 if it is more than 7 it is basic this one is most
basic and basicity decreases as it comes near to 7 similar to that here
also this 'one' is most acidic and 6 is least acidic. now the pH normal plasma pH
the normal pH range of our blood or plasma is 7.35 to 7.45 if the pH
decreases from 7.35 it is called acidemia and if pH increases from
7.45 it is called alkalemia. So this was about the concept of pH. if you liked
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