thermaldynamically or kinetically stable?

solidacid

hi
I have a question about thermodynamic and kinetic stabiliy. for the general materials we can calculate the free energy and k for evaluation of thermaldynamical and kinetical stabiliy. however, for some strange compond, it is impossible to find the enthalpy and entropy to calculate the fre energy.

so could someone give me a advice to solve this problem?

thank you
!!!

Mapes

Can you be more specific, if you're talking about a certain compound? Maybe someone here has experience working in that area.

There are two ways to get detailed energy and entropy information about a new compound: perform experiments and run simulations.

solidacid

Thanks a lot.
my material is dihydrogen phosphites e.g. NH4H2PO3 and KH2PO3. Phosphites are widely used as furtilizers, so few people are interested to their thermo properties. Even I checked several physical chemistry handbooks while no useful information was found. :(

could you give me more detials how to get the entropy or free energy information?

Mapes

Try Barin's Thermochemical properties of inorganic substances (H=-1568 kJ/mol, S=134.9 J/mol-K for potassium dihydogen phosphate) and Lange's Handbook of Chemistry (H=-1445 kJ/mol, S=152.0 J/mol-K for ammonium dihydogen phosphate).