Thermodynamic properties of ammonium methanesulfonate

Highlights: • Temperature dependence of NH₄SO₃CH₃ heat capacity was defined. • Enthalpy of NH₄SO₃CH₃ dissolution in water at 298.15 was obtained. • The main thermodynamic functions of NH₄SO₃CH₃ were calculated. • The standard functions of NH₄SO₃CH₃ formation at 298.15 were determined. • A second-order phase transition of NH₄SO₃CH₃ was observed. Molar heat capacity of ammonium methanesulfonate NH₄SO₃CH₃ was measured in the temperature range from 8.51 to 345.47 K by low-temperature vacuum adiabatic calorimetry. Heat capacity and the main thermodynamic functions (heat content, entropy and Gibbs energy) of NH₄SO₃CH₃ in solid state were tabulated as a function of temperature from 10 K to 340 K. Enthalpy of NH₄SO₃CH₃ dissolution in water was determined at 298.15 K by means of solution calorimetry. On the basis of the experimental data, the standard entropy, enthalpy and Gibbs energy of NH₄SO₃CH₃ formation at 298.15 K were calculated. A second-order phase transition of NH₄SO₃CH₃ was observed by adiabatic calorimetry at T = 272.6 ± 0.5 K.