00:01
Okay, let's see if i wrote this down.
00:01
We are asked to calculate the ph of a solution.
00:03
The result, we mix 15 mils of 0 .28 molar formic acid.
00:07
Got it? and 30 mils of 0 .14 molar sodium hydroxide.
00:12
We are also given that the ka for formic acid is 1 .8 times 10 to the minus 4.
00:20
So let's go ahead and write down what our equation here will be.
00:24
I like to put my acid first.
00:31
I'm going to do this over and this will produce.
00:50
And then i'm going to cross off my spectator ions and change this to oh minus and hcoo minus.
00:58
Okay, so i have for my hco, i have, or my formic acid, i have 15 .0 milliliters and 0 .28.
01:15
Let's do this.
01:38
And that will be 0 .015 times 0 .28.
01:44
This will be 0 .0042 moles of formic acid.
01:55
For my sodium hydroxide, i have 30 milliliters of 0 .14.
02:12
Oh, that's going to be stoichiometrically equivalent.
02:21
Is 0 .0042 moles of my hydroxide.
02:45
So let me think about doing an ice table here.
03:06
So this will be 0 .0042, 0 .0042 and zero, and that'll be plus 0 .0042.
03:36
I'm a little unhappy with this.
03:38
Hang on.
03:39
Okay.
03:39
Let's see if i wrote this down.
03:40
We are asked to calculate the ph of a solution.
03:42
The results we mix 15 mils of 0 .28 molar formic acid.
03:46
Got it? and 30 mils of 0 .14 molar sodium hydroxide.
03:51
We are also given that the ka for formic acid is 1 .8 times 10 to the minus four.
03:56
I am now going to end up with 0 .0042 moles of my anion.
04:10
And i'm going to divide that by my total milliliters, which will be 30 .0 milliliters plus 15 .0 milliliters times 1000 milliliters per liter.
04:27
And 00 .0042 divided by 0 .045 will be equal to 0 .0936 molar hcoo minus...