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# Volume increase from liquid to gas. Watch

1. Just want to make sure I'm understanding this right...

'When a liquid boils at atmospheric pressure its volume increases by a factor of 1000... If the diameter of a molecule is d, it follows that the average separation of molecules in the gas is about 10d.'

So, are we saying that this is the average separation of molecules (10d), and that due to 3-dimensional space the volume increase factor is, thus, 10^3 (1000).

If so, fine. I just can't see why they wouldn't talk about the separation factor first, seeing as that's what causes the volume increase factor. If I'm missing something, please help me
2. why does it matter which way round they said things?
3. (Original post by SwingOnTheSpiral88)
why does it matter which way round they said things?
I just find it easier to understand when they talk about a cause before a consequence. With how it's written I'm not sure I've understood it right, which is why I'm asking here.
4. (Original post by shorty.loves.angels)
I just find it easier to understand when they talk about a cause before a consequence. With how it's written I'm not sure I've understood it right, which is why I'm asking here.
well it sounds fine to me as long as we assume they started with an initial separation of d.
5. (Original post by SwingOnTheSpiral88)
well it sounds fine to me as long as we assume they started with an initial separation of d.
The separation is 10d, (d being the diameter of the molecule) which would be right as 10^3 (due to 3 dimensions) is 1000(d). Right?
6. yeah it says the separation of the gas molecules is 10 d, so they must have been separated by one d when they were in the liquid?

initial volume: d * d * d = d^3

final volume: 10d * 10d * 10d = 1000d^3
7. (Original post by shorty.loves.angels)
The separation is 10d, (d being the diameter of the molecule) which would be right as 10^3 (due to 3 dimensions) is 1000(d). Right?
yep, sounds right to me.
8. (Original post by SwingOnTheSpiral88)
yeah it says the separation of the gas molecules is 10 d, so they must have been separated by one d when they were in the liquid?

initial volume: d * d * d = d^3

final volume: 10d * 10d * 10d = 1000d^3
I'm not entirely sure what you're getting at with the initial volume part.

That would only hold if the separation of molecules in a liquid was equal to the diameter of the molecule, wouldn't it? I've not actually read anything about the volume of a liquid yet so I have no idea if that's true or not.

(Original post by R.Fanatic)
yep, sounds right to me.
Thank you, appreciated.
9. (Original post by shorty.loves.angels)
I'm not entirely sure what you're getting at with the initial volume part.

That would only hold if the separation of molecules in a liquid was equal to the diameter of the molecule, wouldn't it? I've not actually read anything about the volume of a liquid yet so I have no idea if that's true or not.
you are talking about a volume of particles expanding. they have some initial separation, that much you must agree on. If they expand cube-style to a volume 1000 times that of their inital volume, then they have moved to a separation 10 times that of their initial separation along x,y and z.
If their final separation is 10d, then their initial separation must have been d.

I agree that there is nothing to say that the separation of molecules in a liquid has to be equal to their diameter, this must be a specific example. It may be that their separation in liqud state tends to be roughly about their molecular diameter, but this is certainly not a concrete rule, and would also depend on the temperature of the liquid.
10. (Original post by SwingOnTheSpiral88)
you are talking about a volume of particles expanding. they have some initial separation, that much you must agree on. If they expand cube-style to a volume 1000 times that of their inital volume, then they have moved to a separation 10 times that of their initial separation along x,y and z.
If their final separation is 10d, then their initial separation must have been d.

I agree that there is nothing to say that the separation of molecules in a liquid has to be equal to their diameter, this must be a specific example. It may be that their separation in liqud state tends to be roughly about their molecular diameter, but this is certainly not a concrete rule, and would also depend on the temperature of the liquid.
Yeh I think your second paragraph pretty much sums up what I was thinking. We are also referring to the molecules being at atmospheric pressure at this point so I'm guessing the 'initial separation' could be dependant on many variables, temperature and pressure included.
11. (Original post by shorty.loves.angels)
Yeh I think your second paragraph pretty much sums up what I was thinking. We are also referring to the molecules being at atmospheric pressure at this point so I'm guessing the 'initial separation' could be dependant on many variables, temperature and pressure included.
I had a feeling this was going to come up actually, I think your textbook or whatever it is has caused some needless confusion by implying that molecular diameter has to be equal to molecular separation in a liquid. Infact, I'm sure there is some "bucket chemistry" you could carry out at home if you wanted to convince yourself of this.

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