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concentrated acid ,that is from 15 to 20 molar.
so,just imagine what the chemist have done here?
taken a very safer side.
he knew the plans you are having.
so, he took only 1 molar that means a very dilute solution.
of HCL.
other wise 1molar ,very dilute solution of a base.
please ,bear with me you will learn it ,1M HCL means the H ion concentration is having a value of 1M.
now, do not forget that container,container means ionic product of water that is Kw.Kw always say that whatever you do
KW always says that whatever you do. So you run ,you fly, you dive whatever you do i will not change my value.what is that?
10--14.
no matter you have taken one molar H ions
i will some OH ions along with this 1 molar
this number should not change.
you said this is my value
1 molar.so, immediately Kw adjust OH ions and says that this is my value.
so that ,what is Kw?it will not allow itself to change.
should i repeat ?
so,what is the nature of the solution now?
just judge these two values.
1 is far far far beyond 10 -14.
what is to say then?
acidic,that is why it is an acidic solution.
ok,but practically writing this hesitate us because we are from maths. background.
so it is not very easy to digest it .
we will have a discussion,ok let us do that discussion.
H2O reversibly giving H ions and OH ions.
what is the value ?10 -7.
ok, then what happened ?i added HCL,how many H ions it has given?1,
now i have to calculate OH ions but before that a thought will come that when i am adding HCL,which has a value of H ion 1,CL ion,i am not bother for CL ion,its ionic product is related to only these two.
so,a thought will come in the presence of this one,equilibrium will go in backward direction
because you are adding product into product.
so, le t me say that some x is lost ,10 -7 -x loss
and here also 10 -7 -x is lost
but what is the total values of H ion 1+10-7.
now you please compare 1+10-7,what is the sense of doing it?
+.00000000....if you add these two -x,this is the value i am talking about ,this value is as it is 10-7 -x
then what should i write?1.oo..1.
ok,you could have said that better you name this one why are you are confusing as ,this one has no significant leave this
so, when just remove this ,i find this is one very big value
so, when just remove this ,i find this is one very big value
1-x+10-7 -x ,
that means in front of this 1,this 10-7 which i ignore from there some quantity is lost ,lost quantity is further smaller and can be very easily ignored.
that means the H ions value is actually 1,
so theoretically speaking ,once you added acid into water
some ions available all are from acid not from water.
even though few were there but they are pushed back by a lot of H ion which are coming from here
so, practically these H ions which produced from water also rushed back along with the OH ions.
due the stress
so what is your learning ?the learning is that we can directly plug this value here for practical purposes
there is no need to do this kind of exercise
in practical purposes w can directly plug this value the value of H ions if it is far ,if it is one ,even smaller than one
then also we can plug it ,we can get this values ,
well now very simple exercise i am doing,then you will understand it
please listen,
this is neutral water
for which i want to write H ion = OH ions.
and what is the value 10 -7.
one extreme acidic water
what is the value H ion multiplied by OH ions is 10 -14 .but this is given 1M .
IF I PUT THE 1 HERE,OH ions will be 10 -14.
so,what is your understanding in this acidic solution H ion concentration is 1,but OH ion is 10-14.and if i get the value of PH ,PH should be zero.
and if i go like wise,so what you understand here ?the values are decreasing.
so, let me write here ,please ,i am writing H ion concentration,this is 1, 10-1,10-2,10-3,...10-7,
then here H ions 10-8,10-9,....10-14.
what is this these all are the H ion concentration ,ok now although but still i will do that OH ions concentration
tell me 10-14,10-13,10-12......10-1,1.
what these are ,these are OH ion concentration this H ion concentration,very important discussion we are going to do.
what these are ,these are OH ion concentration this H ion concentration,very important discussion we are going to do.
at neutral water ,what is the relation ?
these both are equal
if you go to this side see this side is going greater .....greater.
and the gap of greaterness is widening,that's why i have drawn this line in a widening manner
ok,now look here this side ,this is going to be greater ,greater.....greater.and the gap is also widening
so let me ask some question ,now i am going to write PH values ,PH=1.PH=2...LIKE THIS I WILL GO THIS IS ph =7.
this is PH=14,i hope you don't mind this PH=10,ok,here this is 14,this is PH =3,CAN YOU TELL ME PH=7,what i the nature of solution?
neutral.
PH=10,basic,PH=12 basic,basic PH=14 ,basic,ok down PH =3,ACIDIC,ph=5,acidic,PH=2 acidic.PH=1,acidic.good.
this is one thing but this is not sufficient if you are really preparing for the JEE,TIS EVEN THE 11,12 class student know,
we should quantify our talk when i move from one value to another value.listen when i am at 7,and moving to 6 ,i should say that the PH=6 solution has 10 times more H ions than PH=7.
TELL ME IF I MOVE FROM PH =6 to PH =5,again 10 times ,and then PH =4,again 10 times ,so can you tell me that if i move 6 to 5,how many 10 times i am taking ?10x here 10x here
so 7 to 5 10x here 10x here ,100 times
so,can you tell me that if i am moving from PH=6 to PH=1,how many times the solution becomes more acidic?
10 to power 5 times ,1 lakh times exactly
now very important point suppose i am saying 200 time more acidic than PH= 6,please look hare,i want to use a tool ,i will separate this 200,i will write in special style which can help me to solve the problem
i have to go down by a log. value of 2 and 100,log. value of 100 is 2 and log 2 is .3010,that means from PH=6,which is a value of 6,i have to move down an amount of 2.3010,
there i shall be standing 4.6090,
started from 6 and reached here
suppose i say that i am changing the solution which is at PH= 6,i am diluting this solution.
or i am concentrating which of the two i should speak?
diluting or concentrating ...concentrating...very good.
because as i go down ,the acidic character is increasing that means per drop ,there is a drop of this solution then these dots are representing the H ions.
i am taking the same type of drop here ,H ions are few
so in a single drop,number of H ions are increasing in what multitudes
that is answered by this log. shift
let me ask you are at solution of PH =6.
and you are diluting ,you are concentrating it 2000 times ,where you should stand on the PH scale?
2000 times it is been concentrated
what should be the PH?the ans. simple ,i will translate this 2000 into log. form as 30 so 3,1000 means 3,
and log.2 value ,i can write it like this 2*1000,for 1000 i will write 3.for 2 i write .3010 the value is 3.3010, i have to subtract 3.3010 from 6
i will get 2.6090,i will be somewhere here.
can you tell me?if i concentrate PH=6 solution 40000 times,where will i go?