Talk:Loschmidt constant

From Wikipedia, the free encyclopedia

WikiProject Physics This article is within the scope of WikiProject Physics, which collaborates on articles related to physics.
??? This article has not yet received a rating on the assessment scale. [FAQ]
??? This article has not yet received an importance rating within physics.

Help with this template Please rate this article, and then leave comments to explain the ratings and/or to identify its strengths and weaknesses.

As far as I remember, the Loschmidt constant or number is nothing else but the Avogadro constant. It looks quite strange to call the number of atoms in a gas per cubic meter a constant, since it's only constant at a given pressure and temperature for an ideal gas. --88.68.121.16 18:53, 7 September 2007 (UTC)

[edit] Relationship to Avogadro's Number

The formula given in the article for the relationship between Avogadro's Number and Loschmidts number is:

N(a) = n(0) p/kT

This cannot be right, the first formula has:

n(0) = p/kT

resulting in:

N(a) = n(0)^2

Which is obviously wrong. I am going to make an edit now to correct this. Spinningspark 21:41, 2 October 2007 (UTC)

[edit] Confused

By [1] p. 139, it states that Loschmidt's number is Avogadro's number divided by 22,400. I am confused.--Filll (talk) 21:20, 12 March 2008 (UTC)

From the Avogadro's constant article;
N_A = 6.02214179 \times 10^{23} \quad molecules/mole\,\!
According to your book;
n_0 = \frac {N_A}{22400}=\frac {6.02214179 \times 10^{23}}{22400}=2.6884562\times 10^{19} \quad molecules/ml
Converting that to per cubic metre;
n_0 = 2.6884562\times 10^{25} \quad molecules/m^3\,\!
Which is a fair approximation to the CODATA value quoted in the article of;
n_0 = 2.6867774\times 10^{25} \quad molecules/m^3\,\!
Hope that helps you. But note also that this numerical relationship only holds at standard temperature and pressure. Avogadro's constant is absolutely a constant regardless of temperature and pressure. The number density, on the other hand, varies with temperature and pressure and is only equal to Loschmidt's constant at NTP. SpinningSpark 21:38, 13 March 2008 (UTC)