00:01
Hello student, the question is for the titration of 250 ml of 0 .2 mall per liter h with a solution of one molar and nerve h.
00:08
First, what is the ph at half equivalent point? we are going to calculate ph at half equivalence point, that is equivalent point.
00:23
Ph is equal to pk.
00:25
We are going to use ph is equal to pk and k value which is given in the question, 6 .3, multiply by 10k power minus 4.
00:33
We are going to use pkka is equal to minus logg multiply by ka and put the value of k in this formula.
00:43
Minus log multiply by 6 .3 multiply by 10k power minus 4, we get pka value which is equal to 3 .201.
00:54
It means p .h is equal to 3 .20.
00:58
That is the answer.
01:00
And the b part, what is the? the ph at the equivalent point.
01:03
We are going to calculate.
01:04
Firstly, find the volume of nah used to reach at equivalent point.
01:10
We know that mv is equal to mv, means m1 v1 is equal to m2 v2.
01:19
M1 v1 which is used to for fh and m2 v2 which is used for naoh.
01:26
We know that the molarity of hf is 0 .2, which is 0 .2, multiply by volume of fluorine that is hf that is 250 ml and molarity of naa that is what one molar and multiply by volume we are going to find out when we calculate we get volume 50ml of na oh h that is volume of n a oh h now which is given in the condition firstly m is equal to m hf which is that is mhf which is 0 .2 molar volume that is hf is equal to 250 mll and and no which is equal to one molar and v volume n o h that is equal to 50 ml now we are going to calculate the what mall of n o h that is 50 mall now we are going to calculate mall of hf that is equal to mv.
02:41
Mv.
02:42
It means 0 .2 molar multiplied by 250 ml that is 150 mill that is what 50 mill that is equal to now malls of mall of n -o -h that is multiply m multiply v it means that is that is that is is equal to 1 mall multiplied by 50 ml where we get 50 m more we have we know that we have what we have mall of hf that is 50 or m millimol and m of an that is what 50 millie more it means 50 millimol of both will react to foam will react to form will react to form f negative and h2o and h2o...