00:01
Okay, so this question actually calculate, ask us to calculate the equivalent constant.
00:08
So it says we have a concentration of the weak acid, which is 0 .185, and the ph of this solution is 2 .95.
00:22
So from the ph, we can know is the concentration of the proton is actually around 10 to minus 2 .95.
00:34
And the first step we can do is just write down the dissociation of the weak acid.
00:41
So the weak acid will form hydrogen, iron right, proton, and the anise.
00:51
So we have a quidium constant, which is what we've gone on, calculate.
00:57
So here we know we can actually first set the concentration c is here, right.
01:05
Initially, you have the concentration of ha and once it did, once actually t equals to zero and t equals to equilibrium, once you reach the equivalent sums of ha will actually decompose.
01:23
So we can set the amount of the h .a.
01:26
Decompose is x.
01:27
And you can see the ratio of the one -to -one through the chemical equation.
01:31
So we know the concentration of the proton and h -minors should also be x.
01:38
And actually, you find out in the equivalent, the concentration of h plus the proton is actually equals to 10 to minus 2 .5.
01:51
So now we can start express the k here.
01:56
So the k, the quim constant, equals to the concentration of proton times the concentration of the anite over the concentration of the h.
02:13
And this equals to, so here we know the concentration here is 10 -2 minus 2 .95, and the concentration here is the same...