Dilution and Avagadro

[Jon_in_london]

So if I dilute something by a factor of avagadros number/constant. There is less than a 50% chance that there exists even 1 molecule of the original solute left, as I have been informed.

Why is this so? why avagadro's constant? I thought this number was arrived at fairly arbitrarily by determinig how many C12 atoms are in 12 g of C12.

So what so special about it?

 

[JamesM]

So if I dilute something by a factor of avagadros number/constant. There is less than a 50% chance that there exists even 1 molecule of the original solute left, as I have been informed.

Perhaps I'm misunderstanding you, but if I diluted something by a factor of 2, there would be half the substance left, right? And if I diluted something by a factor of 4, there would only be a quarter of the solute left.

So if I were to dilute something by a factor of the Avogadro constant, there would only be 1/6.022e23 of the solute left. Which would correspond to 1 molecule only if you began with a solution containing 1 mole of the substance (which is defined as approx. 6.022e23 molecules).

So I think whoever informed you of the above, at least in the way it's currently phrased, was wrong. Or I'm wrong. Either way, I look forward to being educated on this matter.

 

[xouper]

Jon_in_london: So if I dilute something by a factor of avagadros number/constant. There is less than a 50% chance that there exists even 1 molecule of the original solute left, as I have been informed.

Why is this so? why avagadro's constant? I thought this number was arrived at fairly arbitrarily by determinig how many C12 atoms are in 12 g of C12.

So what so special about it?

These are questions that have been addressed before on this forum and I am now in the process of putting them in a FAQ on my website.

At the moment I only have one page in my faq, which is an example of how Avogadro's Number can be used:
http://www.xoup.net/faq/watermolecules.php

The next page I have almost completed is "What is Avogadro's Number?" Another question soon to appear in my faq is an explanation of homeopathic dilutions (12X, 12C, 30C, 200C, 1M, etc). Other related questions will follow. And I will certainly consider others if you are interested.

In the meantime, you may wish to look at some of these old threads for information that may apply to your first question:

http://www.randi.org/vbulletin/showthread.php?s=&postid=1869924107#post1869924107

http://www.randi.org/vbulletin/showthread.php?s=&postid=250419#post250419

About your first question above regarding the 50 percent chance, you haven't given enough information to know what you are asking. As worded, it doesn't sound right. Can you clarify or elaborate?

BTW, I concur with the answer given by JamesM.

 

[xouper]

OK, here are some excerpts from my (not quite ready for prime time) faq page on Avogadro's Number:

Jon_in_london: why avagadro's constant? I thought this number was arrived at fairly arbitrarily by determinig how many C12 atoms are in 12 g of C12.

Yes, the International Union of Pure and Applied Chemistry (IUPAC) defines Avogadro's Number as the number of atoms in 12 grams of carbon-12.

According to the National Institute of Standards and Technology (NIST), the 1998 CODATA recommended value for this number is 6.02214199 x 10²³.

In general, Avogadro's Number is the "number of atoms needed such that the number of grams of a substance equals the atomic mass of the substance". http://scienceworld.wolfram.com/physics/AvogadrosNumber.html

In other words, 6.02214199 x 10²³ amu equals one gram.

Does this help?

 

[Jon_in_london]

Re: Re: Dilution and Avagadro

So if I were to dilute something by a factor of the Avogadro constant, there would only be 1/6.022e23 of the solute left. Which would correspond to 1 molecule only if you began with a solution containing 1 mole of the substance (which is defined as approx. 6.022e23 molecules).

I think you got it there.

Thanks.

But- in relation to homeopathey- I often hear people say that after a 10^24 dilution, there isnt any of the original solute left. Are they not strictly correct here?

 

[BillHoyt]

So if I dilute something by a factor of avagadros number/constant. There is less than a 50% chance that there exists even 1 molecule of the original solute left, as I have been informed.

Why is this so? why avagadro's constant? I thought this number was arrived at fairly arbitrarily by determinig how many C12 atoms are in 12 g of C12.

So what so special about it?

One way to get this concept firmly in mind is to forget about the exact definition of Avogadro's constant. Think of the molecules as light-weight marbles. Pour those marbles into a gallon of water, shake it up, take a small amount out and put it into about a gallon of water. Repeat this process over and over. You can easily see that, at some point, there are no more marbles left to pour into the next gallon.

Avogadro's constant simply tells you at what point you run out of marbles. Or, as some skeptical wags might put it, at what point homeopaths have lost their marbles.

Cheers,

 

[xouper]

Re: Re: Re: Dilution and Avagadro

Jon_in_london: But- in relation to homeopathey- I often hear people say that after a 10^24 dilution, there isnt any of the original solute left. Are they not strictly correct here?

That is not correct, since it doesn't specify the volume of the dilution. For example, if I have a gallon of 10²⁴ dilution, I still have 128 molecules of solute in the gallon.

 

[CurtC]

I think the people who use Avogadro's number to explain why homeopathic dilutions almost certainly don't have any molecules of the active ingredient, are putting too much emphasis on that particular number. Sure, if I know how much of something you started with, I would use Avogadro's number along the way, along with the atomic weight of the atoms in one molecule. But the statement that once you dilute anything to 10²⁴ times, there are probably no molecules left, is wrong unless it's specified that you start with one mole of the stuff.

 

[BillHoyt]

I think the people who use Avogadro's number to explain why homeopathic dilutions almost certainly don't have any molecules of the active ingredient, are putting too much emphasis on that particular number. Sure, if I know how much of something you started with, I would use Avogadro's number along the way, along with the atomic weight of the atoms in one molecule. But the statement that once you dilute anything to 10²⁴ times, there are probably no molecules left, is wrong unless it's specified that you start with one mole of the stuff.

To get excruciatingly technical about it, the little vials of homeopathic snake oil that you produce will show a Poisson distribution. The vast majority will have no molecules, many will have one, some will have two and so on.

Cheers,

 

[xouper]

BillHoyt: To get excruciatingly technical about it, the little vials of homeopathic snake oil that you produce will show a Poisson distribution. The vast majority will have no molecules, many will have one, some will have two and so on.

Seems to me, if a one ounce vial of 30C homeopathic snake oil (a common retail size and dilution) that contains one molecule of "active ingredient" is grossly mislabelled, and should be relabelled 12C.

 

[Tez]

I think the people who use Avogadro's number to explain why homeopathic dilutions almost certainly don't have any molecules of the active ingredient, are putting too much emphasis on that particular number. Sure, if I know how much of something you started with, I would use Avogadro's number along the way, along with the atomic weight of the atoms in one molecule. But the statement that once you dilute anything to 10²⁴ times, there are probably no molecules left, is wrong unless it's specified that you start with one mole of the stuff.

I guess the point is, that human size thingy's are always about a mole. The thingys you swallow, the thingys you make, the thingys you throw at people - theyre pretty much mole sized, give or take a factor or two of 10. This is the intuitive reason a mole comes up in these discussions...

Personally I like to point out that there's quite likely a molecule in that vial of water that was once up julius caesars ass (the romans cleaned their butts with wet sponges). Now does the water have a memory of that experience?

 

[jj]

Re: Re: Re: Dilution and Avagadro

But- in relation to homeopathey- I often hear people say that after a 10^24 dilution, there isnt any of the original solute left. Are they not strictly correct here?

Well, we need to know how much of the original solute there was. If there was 1 mole, there is about a 6.022/10 chance of one molecule being left.

One molecule isn't much, to say the least.

One mole of the original substance is as many grams as the atomic weight of the molecule. For many complex organics, this is quite a few grams indeed, and at least some methods I've seen cited for homeopathy use "1 gram" to start with. With "1 gram" the most of a mole you'll ever have (for H2) is a half-mole. With helium, 1/4 mole. With CO2, 1/44th Mole.

But in general to answer the question we have to know how much of the original solute there was in the first place in units of moles.

 

[xouper]

Tez: Personally I like to point out that there's quite likely a molecule in that vial of water that was once up julius caesars ass (the romans cleaned their butts with wet sponges). Now does the water have a memory of that experience?

That sounds like the kind of fun thing I would put in my faq about homeopathic memory of water, except that doesn't seem to be the claim they are making. As I understand their claim, water does not get a memory of a solute molecule until it has been shaken or jarred strongly in a process they call succussion. So unless the water up Julius's butt was "properly succusssed" while there (or shortly after), I am not yet clear that your example directly refutes the homeopathic claim about water memory. But it is a fun example, nonetheless.

 

[xouper]

Re: Re: Re: Re: Dilution and Avagadro

jj: Well, we need to know how much of the original solute there was. ... One mole of the original substance is as many grams as the atomic weight of the molecule. ...

Thank you for confirming what I posted earlier in this thread.

But in general to answer the question we have to know how much of the original solute there was in the first place in units of moles.

Or any equivalent units. For example, is it not sufficient to know the volume of water and the dilution ratio, as in the example I gave previously?

 

[Tez]

That sounds like the kind of fun thing I would put in my faq about homeopathic memory of water, except that doesn't seem to be the claim they are making. As I understand their claim, water does not get a memory of a solute molecule until it has been shaken or jarred strongly in a process they call succussion. So unless the water up Julius's butt was "properly succusssed" while there (or shortly after), I am not yet clear that your example directly refutes the homeopathic claim about water memory. But it is a fun example, nonetheless.

You need to learn to clean your butt a little more vigorously my friend