Simultaneous Determination of Several Thermodynamic Quantities:
K, ∆G°, ∆H°, and ∆S°
Submitted by: Feldan P. Villarta
Submitted to: Mrs. Gloria Jesusa D. Baltazar
Chemistry 73 (Laboratory)
August 11, 2014

Simultaneous Determination of Several Thermodynamic Quantities:
K, ∆G°, ∆H°, and ∆S°
Feldan P. Villarta

I. INTRODUCTION The solubility product constant, Ksp , is the equilibrium constant for a solid substance dissolving in an aqueous solution. It represents the level at which a solute dissolves in solution. A more a substance dissolves, the higher the Ksp value it has. In this experiment, a system of a sparingly soluble salt in water is studied. From the solubility information
A plot of ln K vs 1/T and T vs ∆G were then plotted. From the two plots, the ∆H and ∆S of the reaction were determined.
IV. RESULTS Table 1 displays the data in the titration of borax samples.
Table 1. Titration of Borax Samples
Temperature, K
Trial
Volume of HCl, mL mmol Conc. of Tetraborate

HCl
Tetraborate

300.15
1
15.15
2.74215
1.371075
0.274215

2
15.85
2.86885
1.434425
0.286885
303.15
1
18.50
3.3485
1.67425
0.33455

2
18.95
3.42995
1.714975
0.342995
308.15
1
22.50
4.0725
2.03625
0.40725

2
23.10
4.1811
2.09055
0.41811
313.15
1
26.80
4.8508
2.4254
0.48508

2
26.50
4.7965
2.39825
0.47965
318.15
1
29.45
5.3305
2.665225
0.533045

2
29.30
5.3033
2.65165
0.53033

The calculated solubility product constant Ksp and Gibb’s energy are presented in Table 2. The values calculated are already an average from the two trials in each temperature.

Table 2. Calculated Thermodynamic Quantities
Temperature, K
Ksp
∆G, J/mol
300.15
0.088461566
5792.796038

303.15
0.155793477
4460.15624

308.15
0.281271524
3072.753068

313.15
0.448981689
1949.223383

318.15
0.601226113
1249.248146

The plot of ln K vs 1/T is shown in Figure 1. The equation of the line is y = -10037x + 31.17 with a coefficient of determination value of 0.9704 indicating a fair linearity.

Figure 1. Plot of ln K vs