Heats of combustion of the liquid normal parafin hydrocarbons from hexane to dodecane

Abstract

The measurements were made by means of a bomb calorimeter, which was calibrated electrically for some of the measurements, and by burning standard sample benzoic acid for the remainder. The samples of liquid were inclosed in thin-walled glass bulbs which were flattened on opposite sides, and were ignited by an electric fuse of iron wire. No combustible material other than the iron wire was required to ignite the liquids. Combustible impurities and carbon dioxide were removed from the oxygen before admitting it to the bomb. Measurements of carbon dioxide and carbon monoxide formed in the combustion indicated that the liquids contained very little inert impurity, and that combustion was very nearly complete. The Washburn correction was applied to the results of the calorimetric measurements. The empirical equation-tlFi250 c= 259.28 + 648.84n+ 0.2587n2, where-tlFi250C is the heat of combustion in international kilojoules per mole of liquid normal Cn Fi2n+2 in gaseous oxygen at 25° C and under a constant pressure of 1 atmospher e, the products of combustion being gaseous carbon dioxide and liquid water, also at 25° C, reproduces the mean values within 0.02 percent.

Heats of combustion and formation of the paraffin hydrocarbons at 25 degrees C

“…Corrected to the same unit of energy, their value for n-hexadecane differs from that of Pros en and Rossini [5] by -0.025 ±0.032 percent.…”

“…Consideration of earlier data on the heats of combustion of the paraffin hydrocarbons has already been made [2,3,4,5,7,8,9], except for measurements on n-hexadecane by Richardson and Parks [25]. Corrected to the same unit of energy, their value for n-hexadecane differs from that of Pros en and Rossini [5] by -0.025 ±0.032 percent.…”

“…The factor 0.99955 is the average obtained in t.he experiments on the same compounds described in reference [5], and was there determined as the ratio of the mass of cl),rbon dioxide formed in the combustion to the mass of carbon dioxide calculated stoichiometrically from the mass of the sample. In connection with the data from reference [5], it may be pointed out that the purities of the normal paraffin hydrocarbons measured in that investigation were lower than of the corresponding compounds described in reference [6] by amounts ranging from zero to 0.9 mole percent, as calculated from the freezing points [21] of the compounds measured in reference [5] and the freezing point for zero impurity [22].…”

“…Heats of combustion of n-hexane, n-heptane, n-octane, n-nonane, n-decane, n-undecane, and n-dodecane, in the liquid state, by Jessup [5].…”

Heats of combustion of diamond and of graphite

“…The method of measurement consisted in comparing the rise in temperature of the calorimetric system produced by a measured quantity of energy, with the rise in temperature of the same calorimetric system over approximately the same temperature interval produced by the combustion of a sample of carbon in the bomb. The amount of reaction in each experiment was measured by absorbing the resulting carbon dioxide in Ascarite (a sodium hydroxide-asbestos mixture) and weighing [5,8], using for the atomic weights of carbon and oxygen the values 12.010 and 16.0000, respectively. The glass-stoppered U-tubes containing the Ascarite were filled with hydrogen for weighing, both before and after absorption of the carbon dioxide, in order to minimize the error resulting from uncertainty in the change in volume of the Ascarite upon absorption of carbon dioxide [8].…”