Enthalpies of solution of the nucleic acid bases. 4. Uracil in water
1978; The National Institute of Standards and Technology; Volume: 83; Issue: 6 Linguagem: Inglês
10.6028/jres.083.036
ISSN2376-5259
Autores Tópico(s)Chemical Thermodynamics and Molecular Structure
ResumoAn adiabatic solution calorimeter was used to measure enthalpies of solution in water of 7 uracil samples in a concentration range of 3 to 45 mmol · kg-1 and over a temperature range of 298 K to 325 K. Analytical data for the samples are given. Our best value for the enthalpy of solution is ΔH0(∞,298.15K)=(29.33±1.2)kJmol-1 and for the change in heat capacity for the reaction with temperature, ΔCp0=(57±13)Jmol-1K-1 No change in the enthalpy of solution with concentration was found in this range. Values were calculated for the entropy of solution, ΔS° = (68.1 ± 4.2) J · mol-1 · K-1, and for the apparent molal heat capacity at infinite dilution, Cp20=(178±15)Jmol-1K-1 .
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