00:01
What we need in this reaction to solve this problem is an equation of how the nh3 is reacting with the hno3.
00:09
So if these two are reacted together like they are in a titration, the acid will donate an h to the base.
00:16
So nh3 will become nh4 +, and hno3 will just become nitrate.
00:23
Now let's do an ice chart to kind of show how the moles of these two reactants will change over time.
00:34
So in this ice chart i want to be in moles, not molarity, because we are changing the volume.
00:42
We're mixing the acid and base so the volume is going to get increasingly larger.
00:47
So molarities would not be accurate here.
00:49
So to get the moles for nh3 what we're going to do is take the volume, 0 .100 liters, and we're going to multiply it by the molarity, 0 .10 molarity.
01:01
That is going to give us 0 .010 moles.
01:09
So i'm going to put that in for our amount of nh3.
01:14
I just wanted to show you how i came up with that number.
01:17
It's the molarity times the volume.
01:19
Now in this titration they also added the same volume, 0 .100 liters of hno3, and we want to multiply it by its molarity, 0 .1.
01:35
So once again we're going to get 0 .010 for our moles of acid, and we'll put that up there.
01:46
And we're using two significant figures because the molarities only had two significant figures.
01:52
Initially we have no products here, and these will end up reacting until we run out of something.
02:01
They're in a 1 to 1 mole ratio, so they're both going to decrease by 0 .01, and these products will increase by 0 .010 moles because this is all 1 to 1 mole ratios.
02:14
So at equilibrium we'll have no base, no acid, but we will have made some of this nh4 plus ion and some of this nitrate ion.
02:27
Now the nitrate ion is not really going to change the ph, but this nh4, that will change the ph.
02:36
What's going to happen is the nh4 will undergo something called salt hydrolysis.
02:43
Nh4 will continue reacting with water, and since nh4 is positive it will act as an acid.
02:51
It will donate an h, and it will turn into nh3, and it will change the water into hydronium.
02:58
And what we want to do here though is we want to go back, we want to do an ice chart, and we want to find out what that hydronium is at equilibrium...