00:01
Now here you look at a phase transition, right, of some helium gas into liquid helium, right? so suppose, imagine you have a lot of helium, right, right, a gas, right? the helium gas has a mass which is, according to the question, which is m equals 0 .13 kilogram, right? and everything, of course, is the boiling point.
00:24
The boiling point, let me call it tb, okay? and the boiling points of the of the of helium, of course, you can find the value for the numerical value of this point from a textbook or on the internet, right? i'll leave you to work out there.
00:40
So after this transition becomes just a one liter of liquid helium, right? so this is gas and this is liquid.
00:50
So the question you ask you to work out the entropy change.
00:54
Well, the entropy change consists of two parts.
00:57
First, imagine you squeeze, i mean, imagine this gas becomes just warm, you know, the gas just shrinks, right, just shrinks at the same temperature as thermal into one liter, right? one liter, sorry, not one liter, one liter the volume, right? so this is the founding volume, i could be if.
01:19
And this is the initial volume we could, you can work it out using the equation state for audio gas, right? that is the normal volume point.
01:33
So the normal body point, right, you know that there's also the pb, right? the pressure and the standard pressure at the bottom point and the temperature at the bottom point.
01:43
So you can work out the initial volume, which is a v .i.
01:46
Okay.
01:46
V .i actually is given by, obviously given by the number of the number of helium molecules, i call it n times the border.
01:58
Constant kb and times the temperature to be divided by a pb, okay? from that you can work out the volume...