# Talk:Solvation shell

## Solvation number

I see that some section containing a calculation of the solvation number has been removed due to being unreferenced. I think a cn tag could have been placed instead of removing the useful content.--85.121.32.1 (talk) 08:42, 8 August 2016 (UTC)

Please see WP:BURDEN. Do not restore unsourced content without adding a source. I've pasted it below. Jytdog (talk) 00:33, 14 August 2016 (UTC)

### Unsourced

The following is unsourced. Cut from article and pasted here per V

Solvation number

The solvation number could be determined from the compressibility of the solvent and solution.

${\displaystyle n_{s}=(1-{\frac {\beta }{\beta _{0}}}){\frac {n_{i}}{n_{0}}}}$

where ${\displaystyle \beta }$ and ${\displaystyle \beta _{0}}$ denote compressibilities of solution and the solvent and ${\displaystyle n_{i}}$ and ${\displaystyle n_{0}}$ the amounts of solvate and solvent.

- Jytdog (talk) 00:32, 14 August 2016 (UTC)

The proof steps of this formula can be mentioned here (as mentioned in a Romanian language source which does not make further reference to other language sources). It remains that this formula be harmonized with the below mentioned formula from a Russian source that is also mentioned in another Romanian source where I've encountered without proof.--82.137.9.151 (talk) 18:58, 20 October 2016 (UTC)

First step: definitions

a) the hydration water as a fraction of the total amount of water

${\displaystyle V_{h}=V_{0}{\frac {n_{s}n_{i}}{n_{0}}}}$

b) the compressibility of pure water

${\displaystyle \beta _{0}=-{\frac {1}{V_{0}}}\left({\frac {\partial V_{0}}{\partial P}}\right)_{T}}$

c) the compressiblity of the water in solution excluding the hydration shell water

${\displaystyle \beta =-{\frac {1}{V_{0}}}\left({\frac {\partial (V_{0}-V_{h})}{\partial P}}\right)_{T}}$

d) final formula

${\displaystyle \ n_{s}=(1-{\frac {\beta }{\beta _{0}}}){\frac {n_{i}}{n_{0}}}}$.--82.137.15.250 (talk) 20:25, 20 October 2016 (UTC)

Final steps: substitutions of Vh/(solvation number) from the first definition and the compressibility of the pure solvent/water from the second definition into the third relation and some rearrangements give the final formula.--82.137.14.98 (talk) 20:58, 20 October 2016 (UTC)

### Several formulae harmonization

It seems that there are several derivations which need harmonization. A supplementary formula and derivation is to be found in a Russian language source which waits to be checked as discussed on User talk:R8R Gtrs#Hidration.--82.137.10.242 (talk) 08:29, 6 October 2016 (UTC)

The following formula (from a Romanian source which points to a Russian source) about solvation shell the solvation number z (or ns), densities rho and compressibilities beta, molar masses of water and solution M, M0 and the mass concentration varrho of the dissolved ionic compound:

${\displaystyle z={\frac {\rho -\rho _{0}{\frac {\beta }{\beta _{0}}}-\varrho _{1}}{\varrho _{1}}}{\frac {M}{M_{0}}}}$

needs to be harmonized with the first formula from above. The harmonization has to lead to a unique equation or to show the connection/interconversion between the two equalities.--82.137.15.79 (talk) 19:09, 20 October 2016 (UTC)