00:01
In this problem, we are asked to find the vapor pressure of a spherical drop of water that has a radius of 10 nanometers at 20 degrees celsius.
00:12
We are given the vapor pressure of bulk water at that temperature of 2 .3 kilopascals, and we've got a mass density of 0 .992.
00:24
For our first step, we are going to calculate the volume of a mole.
00:35
In order to do that, we're going to take the molar mass times the density, or divided by the density.
00:49
And i will set that up a little bit more formally as follows.
00:53
Water has a molar mass of 18 .02 grams per mole, and i'm going to make this into meters cubed.
01:10
And my density was 0 .992 grams per centimeter cubed.
01:23
And then i have to cube all the parts of this.
01:27
Let me figure out what this is.
01:29
18 .02 divided by 0 .992 divided by 1 .805 times 10 to the minus 5 meters cubed.
01:50
Next, we're going to use the following equation.
01:58
And i'm going to go ahead and write this on the next page.
02:03
I've started up here.
02:06
Let me see.
02:08
My symbol i think is that's surface tension.
02:20
This is the surface tension of water...