Experiment No. Three

Exp.3 Determination of the Thermodynamic functions
for the Borax Solution
Theory:
The relationship between Gibb’s energy (?G), Enthalpy (?H), Entropy (?S) and the equilibrium constant (K) for a chemical reaction at a specific temperature (T), is shown in equation (1) below.
The Gas Constant, R, is equal to 8.314 J/mol·K.
?G° = – R T ln K = ?H° – T?S° .... (1)
?G° (Std. Gibb’s Energy Change), ?Ho (Std. Enthalpy Change) and ?So (Std. Entropy Change) , ?Ho is a measure of the degree of change in the intermolecular forces and the bond energy for the molecules involved (Exothermic and Endothermic reactions). ?S° is a measure of the change in randomness in the system . ?Go is negative for any reaction for which ?Ho is negative and ?So is positive , therefore conclude that any reaction for which ?Go is negative should be favorable, or spontaneous.
?Go < 0
Conversely, ?Go is positive for any reaction for which ?Ho is positive and ?So is negative. Any reaction for which ?Go is positive is therefore unfavorable.
?Go > 0
A process at constant temperature and pressure will be spontaneous in the direction in which Gibbs energy decreases (–?G°). When equation (1) is rearranged to eliminate ?G°.
log K = ??H° / 2.303RT + ?S° / 2.303R ......(2)
The solubility of a salt is dependent on the temperature of the solution. When equilibrium is established in a saturated solution at a specific temperature, the rate of formation of ions in solution is equal to the rate