Thermochemistry of Zn(AA)SO4 center dot H2O(s) (AA = L-alpha-valine and methionine)

The standard molar enthalpies of dissolution of {znso(4)(.)7h(2)o(s)+val(s)}, {znso(4)(.)7h(2)o(s)+met(s)}, zn(val)(so4h2o)-h-.(s) and zn(met)so4-h2o(s) (where val is l-alpha-valine and met is l-alpha-methionine) in 2 mol dm(-3) hcl at t = 298.15 +/- 0.001 k have been measured to be delta(d)h(m,l)degrees = 94.588 +/- 0.025 kj mol(-1), delta(d)h(m,3)degrees = -46.118 +/- 0.055 kj mol(-1), delta(d)h(m,4)degrees = -70.619 +/- 0.051 kj mol(-1), delta(d)h(m,5)degrees = 58.415 +/- 0.046 kj mol(-1), respectively. the derived molar enthalpies of formation of the complexes zn(val)(so4h2o)-h-.(s) and zn(met)(so4h2o)-h-.(s) are delta(f)h(m)degrees[zn(val)(so4h2o)-h-., s] = -1851 +/- 2 kj mol(-1) and delta(f)h(m)degrees[zn(met)so4 (.) h2o, s] = -2069 +/- 0.7 j mol(-1). (c) 2005 elsevier b.v. all rights reserved.