sodium thiocyanate solution 1

[grandmanitou]

Hi,

Im presently working on a process of making solution of NaSNC-water in a large tank. For the design purpose, I must determine the heat loss when the NaSNC will be added to hot water. Do anybody know if this will create a endothermic reaction, like other sodium product.

 

[NeedAHoliday]

grandmanitou,

Heat of formation of aqueous NaCNS is -160.06 kJ/mol (Ref Perry's 7th Edn)
Heat of formation of crystal NaCNS is -167.22 kJ/mol (Ref Perry's 7th Edn)

Heat of dissolution of NaCNS(s) --> NaCNS(aq) is sum of products minus reactants

dH = -160.06 - (-167.22) = +7.16 kJ/mol

As dH is +ve then the dissolution of NaCNS(s) is endothermic as you suggested. From here you can use the total moles in solution to determine the total energy required to drive dissolution of NaCNS and from here determine the temperature drop in your solvent (water in this case).

Hope this answers your query.

Cheers

 

[grandmanitou]

Hey thank you,
I did not think I would get a good anwser that fast!

 

[handee]

Great answer, Holiday. Strictly speaking, heat of solution is a function of concentration, but your method provides the heat of solution at infinite dilution, which is the worst-case scenario anyway!

Fran McConville
author of the Pilot Plant Real Book

http://www.pprbook.com