A CORRELATION BETWEEN THE THERMODYNAMIC PARAMETERS OF 1-BUTANOL, 2-BUTANOL, l-PROPANOL MOLECULES AND THEIR INFRARED SPECTRA


Authors: Atanas Todorov Atanasov, Antoniya Stefanova Petrova
Keywords: IR spectrum, Gibbs free energy, enthalpy, entropy

Abstract:
The method is based on the thermodynamic parameters of the molecules- standard molar Gibbs free energy change of molecular formation ΔGf0 (kJ/mol), standard molar enthalpy change of molecular formation ΔHf0 (kJ/mol) and standard molar entropy of molecule S0 (J/mol·K). From these thermodynamics parameters the vibrational modes in infrared diapason can be calculated using TG=ΔGf0/S0 and TH=ΔHf0/S0 ratios, considered as ‘apparent’ temperatures. After conversion of the thermal energy kTG or kTH (k is Boltzmann constant) to energy of electromagnetic quanta E=hν (h is Planck constant), an frequencies in infrared spectral range are derived 1/λ=kTG/ch (cm-1), where λ= c/ν (c is speed of light). The calculated frequencies coincide with the vibrational mode on infrared spectrum of given corresponding molecule. The difference between the theoretically calculated frequencies and the experimentally measured ones in the infrared spectra of the studied molecules is within 50 cm-1.Download article