00:01
This question is 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
Now, 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...