00:01
This question asked us to calculate some energy associated with phase changes.
00:05
So in this case, the phase change is vaporizing or boiling water.
00:11
And we're provided with some information here that the density of liquid water is 1 .00 grams per milliliter, and that we have a 100 .0 milliliter sample of water.
00:23
And we're asked then to determine, based on that sample, how much energy is required to vaporize it.
00:29
So the first thing we need to know is what is the mass of that sample.
00:34
So we can use the density information.
00:37
It's a one -to -one ratio here, so we can see that we would then have 100 milliliters, would convert to 100 grams of water.
00:50
And where do we go from there? well, we looked up the constant here for the enthalpy of vaporization of water, and we found that it requires 40 .65 kilojoules.
01:01
Of energy for every mole of water.
01:04
Well, we know how many grams of water we have.
01:07
We need to find out how many moles that converts to then.
01:10
And so we need the molar mass of water.
01:14
So the periodic table is going to help us with that...