[jarosite molar volumes & schwertmannite thermo data]

I just have a quick question regarding the molar volume in 'thermo.dat' of the jarosites

 

I have coppied and pasted the values:

 

Jarosite-K type= sulfate

formula= KFe3(SO4)2(OH)6

mole vol.= 153.200 cc mole wt.= 500.7983 g

5 species in reaction

2.000 SO4-- 3.000 Fe+++ 6.000 H2O

1.000 K+ -6.000 H+

-5.8197 -8.8889 -12.4748 -15.7308

-18.9953 -21.8913 500.0000 500.0000

 

Jarosite-Na type= sulfate

formula= NaFe3(SO4)2(OH)6

mole vol.= 469.050 cc mole wt.= 484.6898 g

5 species in reaction

2.000 SO4-- 3.000 Fe+++ 6.000 H2O

1.000 Na+ -6.000 H+

-4.8714 -4.8714 500.0000 500.0000

500.0000 500.0000 500.0000 500.0000

 

 

My question is how would one obtain a Jar-Na mol vol of 469.050 cc? while Jar-K is 153.200 cc and they are roughly the same mol wt and density.

 

I am also trying to add schwertmannite to this dataset if anyone knows of thermo data that contains it - I am using GWB v6.

 

Thankyou!

 

AJ