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 numbe rs [556-63-8] and [546-89-4]) have been measured by adiabatic intermit tent-heating equilibrium calorimetry from temperatures T near 5 K to 3 50 K and by differential scanning calorimetry (d.s.c.) from 330 K thro ugh 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 cal culated at selected temperatures. At T = 298.15 K the values are: 8.76 8.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 transi tion at T = (495 +/- 1) K, with Delta(trs)H(m)(o) = (222 +/- 5).R.K an d Delta(trs)S(m)(o) = (0.44(9) +/- 0.07).R was confirmed. The present results are briefly discussed in comparison with those previously obta ined on other alkali-metal methanoates and ethanoates.