2 0 2009 yan di 0 journal Original Yang, W.-W.[Wei-Wei] Di, Y.-Y.[You-Ying] Yin, Z.-F.[Zhen-Fen] Kong, Y.-X.[Yu-Xia] Tan, Z.-C.[Zhi-Cheng] Int. J. Thermophys. 2009 2009-04-06 Low-Temperature Heat Capacities and Standard Molar Enthalpy of Formation of Potassium Benzoate C7H5O2K(s) Potassium benzoate C7H5O2K (CAS Registry No. 582-25-2) was synthesized by the method of liquid phase reaction. Chemical and elemental analyses, FTIR, and X-ray powder diffraction (XRD) techniques were applied to characterize the composition and structure of the compound. Low-temperature heat capacities of the compound were measured by a precision automated adiabatic calorimeter over the temperature range from 78K to 398 K. A polynomial equation of the heat capacities as a function of temperature was fitted by the least-squares method. Smoothed heat capacities and thermodynamic functions of the compound were calculated based on the fitted polynomial. In accordance with Hess's law, a reasonable thermochemical cycle was designed, and 100mL of 1 mol * dm?3 NaOH solution was chosen as the calorimetric solvent. The standard molar enthalpies of dissolution for the reactants and products of the supposed reaction in the selected solvent were measured by an isoperibol solution-reaction calorimeter. Finally, the standard molar enthalpy of formation of the title compound C7H5O2K (s) was derived to be -(610.94 +- 0.77) kJ * mol?1. potassium benzoate adiabatic calorimetry heat capacity thermodynamic function isoperibol solution-reaction calorimeter standard molar enthalpy of formation 10.1007/s10765-009-0568-4 30 542-554 1 potassium benzoate C7H5KO2 1 Synthesized by the authors 1 Crystallization from solution Dried by vacuum heating 1 99.1 3 Chemical analysis 2 potassium K 3 hydrogen H2 4 graphite C 5 oxygen O2 1 1 Principal objective of the work RDC TRC 1/22/2009 1 Molar heat capacity at constant pressure, J/K/mol Vacuum adiabatic calorimetry Crystal Direct value, X 1 Author Crystal Pressure, kPa 101.325 6 1 Temperature, K 1 78.05 4 1 64.02 4 1 .19206 1 79.77 4 1 65.4 4 1 .1962 1 82.44 4 1 67.11 4 1 .20133 1 85.05 4 1 69.06 4 1 .20718 1 87.58 4 1 70.57 4 1 .21171 1 90.05 4 1 72.16 4 1 .21648 1 92.46 4 1 73.51 4 1 .22053 1 94.82 4 1 75.08 4 1 .22524 1 97.13 4 1 76.49 4 1 .22947 1 99.4 4 1 77.52 4 1 .23256 1 101.6 4 1 78.59 4 1 .23577 1 103.8 4 1 79.84 4 1 .23952 1 106 4 1 81.03 4 1 .24309 1 108.1 4 1 82.38 4 1 .24714 1 110.2 4 1 83.34 4 1 .25002 1 112.2 4 1 84.3 4 1 .2529 1 114.2 4 1 85.15 4 1 .25545 1 116.3 4 1 86.65 4 1 .25995 1 118.3 4 1 87.5 4 1 .2625 1 120.4 4 1 88.67 4 1 .26601 1 123.5 4 1 90.49 4 1 .27147 1 127.5 4 1 92.84 4 1 .27852 1 131.5 4 1 94.64 4 1 .28392 1 135.4 4 1 96.31 4 1 .28893 1 139.4 4 1 98.35 4 1 .29505 1 143.3 4 1 100.4 4 1 .3012 1 147.2 4 1 102.3 4 1 .3069 1 151.1 4 1 103.9 4 1 .3117 1 154.9 4 1 105.6 4 1 .3168 1 158.6 4 1 107.2 4 1 .3216 1 162.3 4 1 108.9 4 1 .3267 1 166 4 1 110.7 4 1 .3321 1 169.7 4 1 112.6 4 1 .3378 1 173.3 4 1 114.5 4 1 .3435 1 176.9 4 1 115.9 4 1 .3477 1 180.4 4 1 117.8 4 1 .3534 1 185.2 4 1 119.9 4 1 .3597 1 190.3 4 1 122.8 4 1 .3684 1 194.3 4 1 124.8 4 1 .3744 1 198.3 4 1 127 4 1 .381 1 202.2 4 1 129 4 1 .387 1 206.2 4 1 131.6 4 1 .3948 1 210.2 4 1 133.5 4 1 .4005 1 214.1 4 1 135.5 4 1 .4065 1 218.1 4 1 137.3 4 1 .4119 1 222.1 4 1 139.3 4 1 .4179 1 226.1 4 1 141 4 1 .423 1 230.1 4 1 142.7 4 1 .4281 1 234 4 1 144.9 4 1 .4347 1 237.9 4 1 146.3 4 1 .4389 1 243.1 4 1 149 4 1 .447 1 248.2 4 1 151.2 4 1 .4536 1 252.2 4 1 152.7 4 1 .4581 1 256.1 4 1 154.1 4 1 .4623 1 260.1 4 1 156.2 4 1 .4686 1 264.1 4 1 158.2 4 1 .4746 1 268.1 4 1 160.2 4 1 .4806 1 272.1 4 1 161.4 4 1 .4842 1 276.1 4 1 163.3 4 1 .4899 1 280 4 1 165.1 4 1 .4953 1 284 4 1 166.4 4 1 .4992 1 287.9 4 1 168.1 4 1 .5043 1 291.8 4 1 169.9 4 1 .5097 1 295.9 4 1 171.5 4 1 .5145 1 299.8 4 1 172.8 4 1 .5184 1 303.7 4 1 174.3 4 1 .5229 1 307.8 4 1 176.1 4 1 .5283 1 311.7 4 1 177.6 4 1 .5328 1 315.6 4 1 179.5 4 1 .5385 1 319.5 4 1 180.7 4 1 .5421 1 323.5 4 1 182.2 4 1 .5466 1 327.4 4 1 183.7 4 1 .5511 1 331.4 4 1 185.4 4 1 .5562 1 335.5 4 1 187.1 4 1 .5613 1 339.4 4 1 188.7 4 1 .5661 1 343.5 4 1 190.7 4 1 .5721 1 346.5 4 1 192.2 4 1 .5766 1 349.5 4 1 193.4 4 1 .5802 1 353.5 4 1 195 4 1 .585 1 357.5 4 1 196.3 4 1 .5889 1 361.4 4 1 197.9 4 1 .5937 1 365.3 4 1 199.4 4 1 .5982 1 369.2 4 1 200.8 4 1 .6024 1 373.3 4 1 202.3 4 1 .6069 1 377.4 4 1 203.7 4 1 .6111 1 381.4 4 1 205.6 4 1 .6168 1 385.4 4 1 206.8 4 1 .6204 1 389.4 4 1 208.1 4 1 .6243 1 393.4 4 1 209.9 4 1 .6297 1 397.3 4 1 211.1 4 1 .6333 1 1 Principal objective of the work RDC TRC 1/22/2009 1 Molar heat capacity at constant pressure, J/K/mol Vacuum adiabatic calorimetry Crystal Direct value, X 1 Author Crystal Pressure, kPa 101.325 6 1 Temperature, K 1 80 2 1 66.51 4 1 .19953 1 85 2 1 69.25 4 1 .20775 1 90 2 1 71.99 4 1 .21597 1 95 2 1 74.71 4 1 .22413 1 100 3 1 77.41 4 1 .23223 1 105 3 1 80.09 4 1 .24027 1 110 3 1 82.77 4 1 .24831 1 115 3 1 85.42 4 1 .25626 1 120 3 1 88.06 4 1 .26418 1 125 3 1 90.69 4 1 .27207 1 130 3 1 93.3 4 1 .2799 1 135 3 1 95.9 4 1 .2877 1 140 3 1 98.48 4 1 .29544 1 145 3 1 101 4 1 .303 1 150 3 1 103.6 4 1 .3108 1 155 3 1 106.1 4 1 .3183 1 160 3 1 108.6 4 1 .3258 1 165 3 1 111.2 4 1 .3336 1 170 3 1 113.6 4 1 .3408 1 175 3 1 116.1 4 1 .3483 1 180 3 1 118.6 4 1 .3558 1 185 3 1 121 4 1 .363 1 190 3 1 123.5 4 1 .3705 1 195 3 1 125.9 4 1 .3777 1 200 3 1 128.3 4 1 .3849 1 205 3 1 130.6 4 1 .3918 1 210 3 1 133 4 1 .399 1 215 3 1 135.4 4 1 .4062 1 220 3 1 137.7 4 1 .4131 1 225 3 1 140 4 1 .42 1 230 3 1 142.3 4 1 .4269 1 235 3 1 144.6 4 1 .4338 1 240 3 1 146.9 4 1 .4407 1 245 3 1 149.2 4 1 .4476 1 250 3 1 151.4 4 1 .4542 1 255 3 1 153.7 4 1 .4611 1 260 3 1 155.9 4 1 .4677 1 265 3 1 158.1 4 1 .4743 1 270 3 1 160.3 4 1 .4809 1 275 3 1 162.5 4 1 .4875 1 280 3 1 164.6 4 1 .4938 1 285 3 1 166.8 4 1 .5004 1 290 3 1 168.9 4 1 .5067 1 295 3 1 171 4 1 .513 1 298.15 5 1 172.3 4 1 .5169 1 300 3 1 173.1 4 1 .5193 1 305 3 1 175.2 4 1 .5256 1 310 3 1 177.3 4 1 .5319 1 315 3 1 179.3 4 1 .5379 1 320 3 1 181.4 4 1 .5442 1 325 3 1 183.4 4 1 .5502 1 330 3 1 185.4 4 1 .5562 1 335 3 1 187.4 4 1 .5622 1 340 3 1 189.4 4 1 .5682 1 345 3 1 191.4 4 1 .5742 1 350 3 1 193.3 4 1 .5799 1 355 3 1 195.3 4 1 .5859 1 360 3 1 197.2 4 1 .5916 1 365 3 1 199.1 4 1 .5973 1 370 3 1 201 4 1 .603 1 375 3 1 202.9 4 1 .6087 1 380 3 1 204.8 4 1 .6144 1 385 3 1 206.6 4 1 .6198 1 390 3 1 208.4 4 1 .6252 1 395 3 1 210.3 4 1 .6309 1 1 1 Crystal 2 0 -1 Crystal 3 0 -2.5 Ideal gas 4 0 -7 Crystal 5 -1 Ideal gas Principal objective of the work RDC TRC 1/22/2009 Formation of a compound from elements in their stable state 1 Molar enthalpy of reaction, kJ/mol solution calorimetry 298.15 5 200 3 1 Author 1 -610.94 5 1 .77