화학공학소재연구정보센터
Journal of Chemical Thermodynamics, Vol.26, No.12, 1349-1363, 1994
Thermodynamics of Alkali Alkanoates .10. Heat-Capacities and Thermodynamic Properties of Lithium Methanoate and Lithium Ethanoate at Temperatures from Approximate-to-5-K to 580-K-A
Heat capacities of lithium methanoate and ethanoate (CA Registry numbers [556-63-8] and [546-89-4]) have been measured by adiabatic intermittent-heating equilibrium calorimetry from temperatures T near 5 K to 350 K and by differential scanning calorimetry (d.s.c.) from 330 K through melting (solid to isotropic liquid) to 580 K. Smoothed values of C-p,C-m, Delta(0)(T)S(m)(o), Delta(0)(T)H(m)(o), and Phi(m)(o) were calculated at selected temperatures. At T = 298.15 K the values are : 8.768.R, 9.873.R, 1528.6.R.K, and 4.746.R for HCOOLi, and 11.607.R, 14.412.R, 2065.4.R.K, and 7.484.R for CH3COOLi (R = 8.31451 J.K-1.mol(-1)). No transition was observed in the heat-capacity curves of either salt at T < 490 K. The existence in HCOOLi of a solid-to-solid phase transition at T = (495 +/- 1) K, with Delta(trs)H(m)(o) = (222 +/- 5).R.K and Delta(trs)S(m)(o) = (0.44(9) +/- 0.07).R was confirmed. The present results are briefly discussed in comparison with those previously obtained on other alkali-metal methanoates and ethanoates.