00:01
Hi there.
00:02
In this problem, we are trying to find out the ph of a solution that is 1 times 10 to the negative 7th n .a .o .h.
00:11
N .o .h does dissociate completely, so we don't have to worry about the equilibrium constant here.
00:20
All of that will produce o .h.
00:23
Minus when put in solution.
00:25
So let's go ahead and get started.
00:27
Remember water itself self -ionizes forming.
00:36
H plus, and oh h minus.
00:42
So in this problem, i am going to have the h plus concentration equal x.
00:52
You set that equal to my x.
00:55
And that, of course, would be moles per liter because it's a concentration.
01:00
All right.
01:01
If h plus is x from the self -ionization of water, we would also get x, but then, because we're adding n -a -o -h, we have that 10 to the negative 7th moles per liter.
01:18
So that is going to give us the total amount of oh minus in solution.
01:25
Okay, recall also that the kw for water, in other words, when the concentration of h plus is multiplied by the concentration of oh minus, we will get 10 to the negative 14th, or 1 times 10 to the negative 14th, whichever way you would like to write it...