7/28/2019 10_Thermodynamics of the Solubility of Borax 2009

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Thermodynamics of the Solubility of Borax

Purpose:

To determine the thermodynamic quantities H and S for the solvation

reaction of borax in water, by measuring the solubility product constant over thetemperature range from 55 to15 C.

Na2B4O710H2O(s) 2Na+(aq) + B4O5(OH)4

2(aq) + 8H2O(l)

Introduction:

As you have seen or will see in Thermochemistry (Chapter 18) the free energychange in a reaction, G, is related to the equilibrium constant for the reaction by the

equation

G

= RTln(K) (Chang Eqn. 18.14)

Looking at this equation we see that if the reaction is thermodynamically favored, G