Use of Electrolyte Solution Models
The data below are for the activity coefficients of HCl in aqueous hydrochloric acid solutions as a function of HCl molality at 25°C. Compare the predictions of the Debye-H¨uckel model (Eqs. 9.10-15 and 9.10-16), and the extended Debye-H¨uckel models (Eqs. 9.10-17 and 9.10-18) with these data
| M_{ HCl } | \gamma_{\pm} | M_{ HCl } | \gamma_{\pm} | M_{ HCl } | \gamma_{\pm} |
| 0.0005 | 0.975 | 0.1 | 0.796 | 8 | 5.90 |
| 0.001 | 0.965 | 0.5 | 0.757 | 10 | 10.44 |
| 0.005 | 0.928 | 1 | 0.809 | 12 | 17.25 |
| 0.01 | 0.904 | 3 | 1.316 | 14 | 27.3 |
| 0.05 | 0.830 | 5 | 2.38 | 16 | 42.4 |
\ln \gamma_{\pm}=-\alpha\left|z_{+} z_{-}\right| \sqrt{I} (9.10.15)
I=\frac{1}{2} \sum_{ i = ions } z_{ i }^{2} M_{ i } (9.10.16)
\ln \gamma_{\pm}=-\frac{\alpha\left|z_{+} z_{-}\right| \sqrt{I}}{1+\beta a \sqrt{I}} (9.10.17)
\ln \gamma_{\pm}=-\frac{\alpha\left|z_{+} z_{-}\right| \sqrt{I}}{1+\beta a \sqrt{I}}+\delta I (9.10.18)
