Thermodynamics Research Center / ThermoML | Thermochimica Acta

Enthalpies of formation and lattice enthalpies of alkaline metal acetates

Aleixo, A. I.[Ana I.], Oliveira, P. H.[Pedro H.], Diogo, H. P.[Herminio P.], Minas da Piedade, M. E.[Manual E.]
Thermochim. Acta 2005, 428, 1-2, 131-136
ABSTRACT
The standard (p. = 0.1MPa) molar enthalpies of formation in the crystalline state of the alkaline metal acetates CH3COOM (M = Li, Na, K, Rb, Cs), at T = 298.15 K, were determined by reaction-solution calorimetry as: dfH.m (CH3COOLi, cr) = -(741.40 +- 0.95) kJ mol-1, dfH.m (CH3COONa, cr) = -(711.01 +- 0.51) kJ mol-1, dfH.m (CH3COOK, cr) = -(722.36 +- 0.49) kJ mol-1, dfH.m (CH3COORb, cr) = -(722.31 +- 1.09) kJ mol-1, dfH.m (CH3COOCs, cr) = -(726.10 +- 1.07) kJ mol-1. These results, taken together with the enthalpies of formation of the haloacetates XCH2COOM (M = Li, Na; X= Cl, Br, I) and chloropropionates ClCH(CH3)COOM (M = Li, Na) re-evaluated from literature data were used to derive a consistent set of lattice energies, and discuss some general trends of the structure energetics relationship for the CH3COOM, XCH2COOM, and ClCH(CH3)COOM compounds, based on the Kapustinskii approximation. It was found that the lattice energies of the haloacetates are essentially independent of the halogen and ca. 17 25 kJ mol-1 smaller than those of the corresponding acetates. In addition, no significant difference between the lattice enthalpy values of the haloacetates and chloropropionates was observed. Finally, linear correlations of very similar slope were obtained by plotting the M O bond distances derived from the Kapustinskii equation against the published experimental M O bond distances for alkaline metal acetates and alkoxides. The analysis of these relations suggests that the metal oxygen bond distances for the lithium, potassium, and rubidium acetates, whose molecular structures in the solid state have not been determined, can be estimated as 214, 288, and 304 pm, respectively.
Compounds
# Formula Name
1 C2H4O2 acetic acid
2 ClH hydrogen chloride
3 ClNa sodium chloride
4 H2O water
5 ClLi lithium chloride
6 ClK potassium chloride
7 ClRb rubidium chloride
8 ClCs cesium chloride
9 C2H3LiO2 lithium acetate
10 C2H3NaO2 sodium ethanoate
11 C2H3KO2 potassium ethanoate
12 C2H3O2Rb rubidium acetate
13 C2H3CsO2 cesium acetate
Datasets
The table above is generated from the ThermoML associated json file (link above). POMD and RXND refer to PureOrMixture and Reaction Datasets. The compound numbers are included in properties, variables, and phases, if specificied; the numbers refer to the table of compounds on the left.
Type Compound-# Property Variable Constraint Phase Method #Points
  • POMD
  • 9
  • Molar enthalpy of transition or fusion, kJ/mol ; Crystal
  • Crystal
  • Liquid
  • Air at 1 atmosphere
  • DSC:FP
  • 1
  • POMD
  • 9
  • Normal melting temperature, K ; Crystal
  • Crystal
  • Liquid
  • Air at 1 atmosphere
  • DTA:FP
  • 1
  • POMD
  • 10
  • Molar enthalpy of transition or fusion, kJ/mol ; Crystal
  • Crystal
  • Liquid
  • Air at 1 atmosphere
  • DSC:FP
  • 1
  • POMD
  • 10
  • Normal melting temperature, K ; Crystal
  • Crystal
  • Liquid
  • Air at 1 atmosphere
  • DTA:FP
  • 1
  • POMD
  • 11
  • Molar enthalpy of transition or fusion, kJ/mol ; Crystal
  • Crystal
  • Liquid
  • Air at 1 atmosphere
  • DSC:FP
  • 1
  • POMD
  • 11
  • Normal melting temperature, K ; Crystal
  • Crystal
  • Liquid
  • Air at 1 atmosphere
  • DTA:FP
  • 1
  • POMD
  • 12
  • Molar enthalpy of transition or fusion, kJ/mol ; Crystal
  • Crystal
  • Liquid
  • Air at 1 atmosphere
  • DSC:FP
  • 1
  • POMD
  • 12
  • Normal melting temperature, K ; Crystal
  • Crystal
  • Liquid
  • Air at 1 atmosphere
  • DTA:FP
  • 1
  • POMD
  • 13
  • Molar enthalpy of transition or fusion, kJ/mol ; Crystal
  • Crystal
  • Liquid
  • Air at 1 atmosphere
  • DSC:FP
  • 1
  • POMD
  • 13
  • Normal melting temperature, K ; Crystal
  • Crystal
  • Liquid
  • Air at 1 atmosphere
  • DTA:FP
  • 1
  • RXND
  • 1
  • 10
  • 2
  • 3
  • Molar enthalpy of reaction, kJ/mol
  • OTHER:Method:OTHER:sMethod:Solution calorimetry
  • 1
  • RXND
  • 1
  • 9
  • 5
  • 2
  • Molar enthalpy of reaction, kJ/mol
  • OTHER:Method:OTHER:sMethod:Solution calorimetry
  • 1
  • RXND
  • 1
  • 11
  • 6
  • 2
  • Molar enthalpy of reaction, kJ/mol
  • OTHER:Method:OTHER:sMethod:Solution calorimetry
  • 1
  • RXND
  • 1
  • 12
  • 2
  • 7
  • Molar enthalpy of reaction, kJ/mol
  • OTHER:Method:OTHER:sMethod:Solution calorimetry
  • 1
  • RXND
  • 1
  • 13
  • 2
  • 8
  • Molar enthalpy of reaction, kJ/mol
  • OTHER:Method:OTHER:sMethod:Solution calorimetry
  • 1