\(T_t = 1000 K.\) \(T_2 = 100\,K\)
\(m = 32\,g\)
\(\Delta S = ?\)
at constant pressure
\(\Delta S = {C_p}\,\ln \,\frac{{{T_2}}}{{{T_1}}}\)
\( = 2.303 \times {C_p}\,\log \,\frac{{{T_2}}}{{{T_1}}}\)
\( = 2.303 \times 10\,\log \,\frac{{100}}{{1000}}\)
\( = - 23.03\,cal\,{\deg ^{ - 1}}\)
$Mg^{2+}(aq) = -456.0; OH-(aq) = -1 57.3; Mg(OH)_2 (s) = -833.9$