00:01
All right, so we have the following solubility curve for some substances in water.
00:04
For question one, why does the x -axis run from zero to 100 degrees? well, it runs from the melting point of water when ice turns into liquid water to the boiling point of water when liquid water would turn into water vapor.
00:18
And the reason is this is the range of temperatures over which water is a liquid, and we want our solvent to be in a liquid state.
00:25
It's irrelevant to, you know, have something dissolving in ice.
00:28
That's not even possible.
00:30
We keep it within the liquid range.
00:32
For question two, what substance is most soluble at 10 degrees celsius? so we'll look at 10 degrees, and we want the one that's going to be highest up, so that's going to be k -i here, has the greatest value on the y axis.
00:50
All right, which two substances are the same solubility at 80 degrees celsius? so we want to find two curves that intersect at 80 degrees.
00:58
So let's see, this one, this one.
01:07
It looks like nacl and kclo3.
01:21
Question 4.
01:23
What's the substance that has the most dramatic change in solubility? so we want to find the one with the change is the slope.
01:31
So we want to find the one with the biggest slope, which in this case is kno3, potassium nitrate.
01:39
Because it goes up really fast, kind of like a curve.
01:44
So it's even more, it's more than first order linear.
01:49
Okay, 5.
01:50
How many grams of sodium nitrate can be dissolved at 30 degrees and 175 milliliters of water? so at 30 degrees and we're looking at sodium nitrate and i -o -3, right here, the solubility, it looks like it's like just over 95.
02:06
So we could say about 96 grams in 100 milliliters of water.
02:14
So if we know that that's the ratio and we want it in.
02:19
In 175 milliliters of water, we can set up a proportion in cross multiply.
02:26
So this is equal to 96 times 175 divided by 100.
02:40
It's going to be 70.
02:42
Wait, that doesn't make sense.
02:45
I think i did something wrong.
02:46
96 times 175, yeah, divided by 168 grams.
02:58
6.
02:59
What's the solubility of potassium chloride at 90 degrees celsius? so at 90 degrees, kcl is this line right here.
03:05
So we're looking, let me make this in red, this line right here.
03:09
So it looks like it's about 55 grams per 100 grams or 100 emils.
03:18
I'm using grams and milliliters of water interchangeably because the density is 1 gram per amount, by the way...