[gmx-users] create a physiological ion concentration

[Lieven Buts]

On Tuesday 11 November 2003 08:27, Anton Feenstra wrote:
> nanyu101 at sina.com wrote:
> >   In my system, the concentration of CaCl2 is about 150-200mM and the
> > water molecules in my system is 7000. If I want to create a 200mM
> > concentration, I have to solve 40 CA2+ cations and 80 CL- anions. Because
> > I have already put 10 CA2+ and CL- in the right place of ion channel,
> > there are only 30 CA2+ and 60 CL- remained.
>
> Is that right, IIRC, water is 70M, i.e. 70000 mM.
> May that explain your problems, or is the 7000mM a typo?

Isn't it about 55M? 18 g/mol, so 1 mole is 18 g, corresponding to a volume of 
about 18 ml; hence the molarity is 1 mol/18 ml =(approx) 55M.

-- 
Lieven Buts
Department of Ultrastructure
Vrije Universiteit Brussel