00:01
So in question 30 we're asked to find the amino acid which has a positive charge at ph 4 plus one charge at ph 4 and neutral at ph 8.
00:11
So if we look at glutamic acid with the following structure, we can see that the pkr at the isoelectric point is 4 .25 and we're told that the ph at 4 .0.
00:55
So this will be a positive is charged because below the isoelectric point these hydrogen atoms will still be intact with these oxygens and anything below ph 4 it will look at look like this structure so at ph 4 we'll have charge plus as plus 1 now if we move above the is isoelectric point which is 4 .25 or the pk a rather we'll see that we're going to form the following structure.
01:54
Now this is at ph 8 .0 with a charge of, if we can't the charge, this is 1, plus 1, and this is minus 1.
02:03
Plus 1 and minus 1 gives you a charge of 0.
02:06
So it's neutral.
02:07
So when it's below the p .kr at 4 .25, at ph 4 .0, it will have a charge of plus 1.
02:17
And if it's above the pqr at ph 8, it will have a charge of 0.
02:23
Now in question 31, we're told to find the pca, given the following ratios of acid to salt at 10, with an initial ph of 10.
02:43
Now, we are going to use this equation...