[Lex Computer & Tech Group/LCTG] why does ice float

[Ted Kochanski]

All,

Not to get too far into QM --- But it's not Chemistry -- it's Physics - -
and then why is the minimum in a V(T) for water found @ 4C [actually 277.13
K] @ atmospheric pressure?
as is the corollary how can we skate on ice

see for example:
Fluid Phase Equilibria Volume 560, September 2022, 113515

Simulation and theoretical analysis of the origin of the temperature of
maximum density of water
D. González-Salgado, E.G. Noya, E. Lomba
Received 11 January 2022, Revised 20 May 2022, Accepted 23 May 2022,
Available online 25 May 2022, Version of Record 1 June 2022.

Abstract

The presence of a maximum in density is one of the well-known anomalies of
water. This maximum is located at 4°C at room pressure and it moves to
lower temperatures as pressure increases. In this work, we attempt to
provide a quantitative explanation of the existence of the temperature of
maximum density, *T*MD, and its dependence on pressure, using a description
in terms of low and high density water states. To that aim, we analyzed
*NpT* molecular dynamics
<https://www.sciencedirect.com/topics/physics-and-astronomy/molecular-dynamics>
trajectories
of TIP4P/2005 liquid water from -1800 bar to 1000 bar, and from 238.15 K to
328.15 K. We computed the mole fractions of the low and high density water
states and their partial molar volumes. We found that the temperature
dependence of both quantities plays a fundamental role in the existence of
the *T*MD. On the other hand, only the variation with pressure of the mole
fractions of the low and high density water is essential to explain the *T*
MD pressure dependence. Additionally, we have also performed an equivalent
analysis using the parameterization of the two-state thermodynamic model
proposed by Biddle *et al.* [J. Chem. Phys. 146, 034502 (2017)] obtaining
similar conclusions.


https://doi.org/10.1016/j.fluid.2022.113515

Ted

On Mon, Sep 16, 2024 at 5:01 PM John P. Rudy via LCTG <lctg at lists.toku.us>
wrote:

> It is just to be funny as Calvin and Hobbes always it
>
>
>
> *From:* Robert Primak <bobprimak at yahoo.com>
> *Sent:* Monday, September 16, 2024 3:09 PM
> *To:* Lex Computer Group <lctg at lists.toku.us>; John P. Rudy <
> jjrudy1 at comcast.net>
> *Subject:* Re: [Lex Computer & Tech Group/LCTG] why does ice float
>
>
>
> As a  degreed chemist, I don't need to look this one up.
>
>
>
> But the Dad Answer looks a lot like ChatGPT made it up.
>
>
>
> -- Bob Primak
>
>
>
>
>
>
>
> On Monday, September 16, 2024 at 12:16:11 PM EDT, John P. Rudy via LCTG <
> lctg at lists.toku.us> wrote:
>
>
>
>
>
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