00:01
For each one of the scenarios, we have to determine the concentration of each individual ion.
00:05
So the first one, we have two different solutions of hydrochloric acid.
00:09
So the only ions we need to know or worry about are h +, and our chloride or cl-.
00:14
Let's start with the first one, where we're going to have to figure out the number of moles.
00:20
So we're going to take 0 .100 and we're going to multiply it by 0 .030 liters.
00:26
Now if we take a look at our units, notice how liters cancel out and you're left with just moles.
00:34
So we take 0 .100 times 0 .030 and this is going to be 0 .003 moles.
00:42
Now let's do the bottom one.
00:45
We have 0 .450 moles per liter and we're going to multiply it by 0 .010.
00:53
So 0 .450 times 0 .010, we're going to end up with 0 .0045 moles.
01:03
Now when we separate out hcl or when it disassociates into its ions, it disassociates fully.
01:13
And everything is one -to -one.
01:15
So if you have 0 .100 molar of hcl, you also have 0 .100 and 0 .100 molar.
01:25
Of each one of your ions.
01:27
In our case, we have things that are combining.
01:30
So we have to first find the number of moles that we have of each constituent and then find the total volume to find the concentration.
01:39
So the total number of moles that we have is going to be 0 .0075.
01:47
So in each case, we have 0 .0075 and that's moles.
01:56
So now we just need liters and we have to find the total volume.
02:00
So we have 30 milliliters plus 10 milliliters equals 40 milliliters or 0 .040 liters.
02:12
So let's do that.
02:13
Let's put that at the bottom of our fraction.
02:19
So we're going to take 0 .0075 and divide it by 0 .040.
02:24
And our final concentrations for each one are going to be 0 .1875.
02:31
Make sure you put your units and of what they are.
02:37
Now let's take a look at b where we have to figure out sodium ions, sulfate ions, potassium ions, and fluoride ions.
02:50
First, let's figure out our total volume because we're going to need that later.
02:57
So we have 15 .0 plus 17 .4.
03:01
Let's add those together and we get 32 .4 milliliters.
03:07
This comes out to be 0 .0324 liters.
03:11
So now let's take a look at what happens when we have sodium sulfate separating into ions.
03:20
It separates out into two sodium and one sulfate.
03:26
So this means for however many x number of moles that you have for sodium sulfate, you're going to have twice x for sodium and just x for the sulfate.
03:37
So let's figure out the sodium sulfate moles.
03:40
So we're going to take 0 .265 moles per liter, multiply that by 0 .0150 liters.
03:53
Liters cancel out, you're left with just moles.
03:56
0 .265 times 0 .015 is going to be 0 .003975.
04:05
Note this is moles of sulfate as well as sodium sulfate.
04:10
We're going to multiply that by 2 and the moles for sodium is going to be 0 .00795 moles of sodium.
04:24
Now let's work with potassium chloride.
04:28
Let's change colors to orange.
04:31
So potassium chloride, we have 0 .200 times 0 .0174.
04:38
0 .2 times 0 .0174, that's going to be 0 .00348.
04:47
And this is moles of potassium ions and chloride ions.
04:52
So now let's work with concentration...