Oxygen Bomb Calorimetry Research Articles

Milk-energy production by lactating mares

Summary Seven Quarter Horse mares were hand milked at 10, 30, 45, 60, 90, 120 and 150 days throughout a 150-day lactation. Milk samples were analyzed for gross energy concentration by oxygen-bomb calorimetry. Average milk-energy concentration over the 150-day lactation was 438.4 (mUg, ranging from 336.8 to 576.5 cal/g. Highest average energy concentration was observed 10 days postpartum and tended to decline linearly as lactation advanced. Milk -energy concentration was related to milk yield (r=.71, P

Foliar heat content variations in four coniferous tree species of central Alberta

Foliar high heat contents were determined by standard oxygen bomb calorimetry in jack pine (Pinusbanksiana Lamb.), black spruce (Piceamariana (Mill.) B.S.P.), white spruce (Piceaglauca (Moench) Voss), and balsam fir (Abiesbalsamea (L.)Mill.) from samples collected in central Alberta. New foliage, sampled in mid-July and early September, and foliage 1, 2, and 3+ years old, sampled in late May, mid-July, and early September, were included in these determinations. The heat contents of the new foliage in all four species as well as the heat contents of the old foliage in jack pine, black spruce, and balsam fir consistently increased with each sampling time, while the heat contents of the old foliage in white spruce at first increased and then decreased between the times. The variations of the heat contents attributed to foliar ages lacked consistency in all four species, although the contents of the new foliage were predominantly lower than the contents of the old foliage. The overall heat contents for the combined sampling times and foliar ages in both the new foliage and the old foliage were the lowest in white spruce and the highest in balsam fir, with black spruce having the second highest content in the new foliage and jack pine having the second highest content in the old foliage.

Thermochemistry of nitrophenols. V. Enthalpies of formation of 2,4- and 2,6-dinitrophenols

Using static oxygen-bomb calorimetry, the standard enthalpies of combustion of the 2,4-and 2,6-isomers of dinitrophenol have been determined as −2697.22 and −2723.08 ± 3.18 kJ mole −1, respectively. Standard enthalpies of formation have been calculated as −235.50 and −209.64 ± 3.27 kJ mole −1, respectively.

Enthalpies of Combustion of Organic Compounds. IV. Acetanilide and Nicotinic Acid

Abstract Standard energies of combustion at 298.15 K have been determined for crystalline acetanilide and nicotinic acid by static oxygen bomb calorimetry. Derived standard enthalpies of combustion and of formation are −(4224.8±1.0) and −(209.5±1.5) kJ mol−1 for acetanilide, and −(2730.83±0.48) and −(344.81±0.92) kJ mol−1 for nicotinic acid, respectively. Nicotinic acid pellets of 1.2 g in mass showed remarkable tendency to spatter when partially burnt. Factors governing the completeness of combustion of the material have been explored through 28 test combustion experiments.

Variation Among Gross Energy Values Measured by Two Modes of Adiabatic Oxygen Bomb Calorimetry

A master control for an adiabatic bomb calorimeter introduces two automatic modes of operation, but little is known about the variances of data derived by each mode. Nine samples were assayed in duplicate using each mode on each of 5 days. The resulting data were subjected to analyses of variance to compare the two modes and to estimate components of variance among and within days. The mode had no effect on the gross energy estimates. When sunflower oil and tallow were assayed, the within-day standard deviation was approximately three times greater with the rapid mode than with the reference mode. None of the other 7 samples showed significant differences between modes. Such day-to-day differences as were observed were not consistent over the materials assayed and cannot be attributed to calorimeter operation nor to environmental changes.For most gross energy measurements of feedingstuffs and excreta, the rapid mode appears to produce satisfactory data of high reproducibility. The rapid mode permits a greater throughput of samples than conventional adiabatic calorimetry equipment or than the reference mode; up to 35 samples per 7.5 hr day are assayed in this laboratory.

Thermochemical Estimation of Destabilization Energies of 1,2-, 1,3-, and 1,4-Dicyanobenzenes Due to Interactions between Substituents. Appendix: Dipole Moments in Solution of the Dicyanobenzenes

Abstract Enthalpies of combustion of 1,2-, 1,3-, and 1,4-dicyanobenzenes were determined by precision oxygen-bomb calorimetry. Enthalpies of sublimation of these compounds were obtained by the measurement of temperature dependence of vapor pressure. The standard enthalpies of combustion ΔHc°(298.15 K)/kJ mol−1 and the standard enthalpies of sublimation ΔHS(298.15 K)/kJ mol−1 are as follows: −4000.36±0.67 and 86.9±1.5 for 1,2-dicyanobenzene; −3992.29±0.75 and 90.1±1.5 for 1,3-dicyanobenzene; −3988.04±0.59 and 88.8±1.5 for 1,4-dicyanobenzene, respectively. Thermochemical destabilization energies were estimated by comparing the derived standard enthalpies of formation in gaseous state with those estimated for hypothetical non-destabilized molecules. They were discussed in terms of electrostatic interactions between highly electronegative and dipolar cyano substituents on one and the same benzene ring. Dipole moments of the dicyanobenzenes in benzene and dioxane solutions are reported in Appendix.

The enthalpies of formation of some bridged-ring polynuclear aromatic hydrocarbons

The enthalpies of combustion of five bridged-ring polynuclear aromatic hydrocarbons were measured by precision oxygen-bomb calorimetry. The following values are reported for the standard enthalpy of combustion, ΔH c o(298.15 K)/kJ mol −1, in the crystalline state: 1,2′-binaphthylmethane, C 21H 16, −(10712.35 ± 1.66); 1′,2′,3′,4′-tetrahydro-1,2′-binaphthylmethane, C 21H 20, −(11166.10 ± 1.53); triphenylene, C 18H 12, −(8949.94 ± 1.19); dodecahydrotriphenylene, C 18H 24, −(10319.19 ± 1.35); and biphenylene, C 12H 8, −(6198.80 ± 0.91). Values of the enthalpy of formation in the crystalline state were derived.

Enthalpies of formation of hafnium carbides

Enthalpies of combustion of hafnium oxycarbides HfC x O y (10 samples; 0.592 ⩽ x ⩽ 0.982; 0.006 ⩽ y ⩽ 0.149) have been determined by oxygen-bomb calorimetry. The dependence of enthalpies of formation of HfC x O y on x and y is described by the equation ΔH f o ( HfC x O y) kcal th mol −1 = 15.4 − 81.8x 1 − 100y , in which x 1 = x at x ⩽ 0.80 and x 1 = 0.80 at x ⩾ 0.80. The results are discussed.

Enthalpies of Combustion of Organic Compounds. II. l- and d-Glutamic Acid

Abstract Enthalpies of combustion of l- and d-glutamic acid in the crystalline state have been measured by oxygen bomb calorimetry. Standard enthalpies of formation at 298.15 K have been determined.

The enthalpies of combustion and formation of 1,8-dimethyInaphthalene, 2,3-dimethylnaphthalene, 2,6-dimethylnaphthalene, and 2,7-dimethylnaphthalene

The enthalpies of combustion of 1,8-dimethylnaphthalene, 2,3-dimethylnaphthalene, 2,6-dimethylnaphthalene, and 2,7-dimethylnaphthalene were measured by precision oxygenbomb calorimetry. The following values, based on the mass of carbon dioxide produced, are reported for the standard enthalpy of combustion, ΔHoo(298.15 K)/kcalth mol−1, of these compounds in the crystalline state: 1,8-dimethylnaphthalene, -(1544.70 ± 0.25); 2,3-dimethylnaphthalene, -(1537.95 ± 0.21); 2,6-dimethylnaphthalene, -(1537.14 ± 0.38); and 2,7-dimethylnaphthalene, -(1537.21 ± 0.23).† None of these values would have been predicatable within experimental uncertainty, and a predicted value for 1,8-dimethylnaphthalene probably would have been different by 7 kcalthmol−1 from the experimental value.

Pyrolysis and combustion of polyester. I. Thermochemistry of poly(1,4‐cyclohexylene dimethylene terephthalate) treated with selected phosphorus‐ and halogen‐containing flame retardants

AbstractA series of poly(1,4‐cyclohexylene dimethylene terephthalate) (PCHDT) fabrics treated with selected phosphorus‐ and halogen‐containing flame retardants has been studied by static oxygen bomb calorimetry. The amount of heat evolved when these fabrics are burned in the open atmosphere has been determined indirectly using calculations based on Hess' law of summation. This heat evolution when corrected for contributions due to burning of the flame retardant appeared to correlate with the efficiency of the flame retardant treatment and was interpretable in terms of mechanisms of flame retardant action. Also, this technique has been applied to blends containing polyester.

Convenient, inexpensive unknowns for oxygen bomb calorimetry

Convenient, inexpensive unknowns for oxygen bomb calorimetry

Pyrolysis and Combustion of Cellulose

A series of cotton fabrics treated with model flame retardants has been studied by static oxygen bomb calorimetry. The amount of heat evolved when these fabrics were burned in the open atmosphere has been determined indirectly using calculations based on Hess' law of summation. This heat evolution was found to correlate with the efficiency of the flame retardant treatment and was interpretable in terms of mechanisms of flame retardant action.

INFLUENCE OF DIETARY VOLATILE FATTY ACID MIXTURES ON PERFORMANCE AND ON FAT COMPOSITION OF GROWING PIGS

Two experiments were conducted to evaluate the acceptability, calculated digestible energy, influence on performance, and effect on fatty acid composition of backfat when a mixture of volatile fatty acids (VFA) or of a sodium salt of these fatty acids (Na VFA) was fed to pigs. The weight percent of the VFA mixture was 40 acetic, 40 propionic and 20 butyric acid. Adding 2 to 8% VFA or Na VFA to the diet, without adjustment for digestible energy or total protein, did not influence feed intake or rate of gain. Dietary levels of 10 or 12% VFA or Na VFA depressed daily gain. When 4% VFA or Na VFA was fed from an initial weight of 12 kg, feed intake was not altered in comparison with that of pigs fed a control diet. Rate of gain averaged 0.64 kg per day for pigs fed either VFA or Na VFA, compared with 0.60 kg for control pigs. The digestible energy values of the VFA and Na VFA, based on calculated energy conversion from 38 to 75 kg liveweight, were higher than the gross energy values of the compounds determined by oxygen bomb calorimetry, presumably because of a synergistic action of VFA with other energy sources in the diet. Carcass backfat thickness, area of loin and lean in the ham face were not significantly altered by feeding VFA or Na VFA. When pigs received up to 12% VFA or Na VFA, weight percent oleic acid in the outer backfat was increased (P < 0.05) from 49.9% in the control pigs to between 52.7 and 53.3 percent. There was no influence on backfat composition when 4% VFA or Na VFA was fed continuously.

The enthalpies of combustion and formation of n-propylcyclopentane and five methylethylcyclopentanes

The enthalpies of combustion of n-propylcyclopentane and five isomeric methylethyl-cyclopentanes were determined by oxygen-bomb combustion calorimetry. The following values, based on the mass of sample, are reported for the standard enthalpy of combustion ΔH°c/(298.15 K)/kcal mol−1 of these compounds in the liquid state: n-propylcyclopentane, −(1253.82 ± 0.18); 1-methyl-1-ethylcyclopentane, −(1252.62 ± 0.22); 1-methyl-cis-2-ethylcyclopentane, −(1253.32 ± 0.22); 1-methyl-trans-2-ethylcyclopentane, −(1252.30 ± 0.20); 1-methyl-cis-3-ethylcyclopentane, −(1252.47 ± 0.22); and 1-methyl-trans-3-ethylcyclopentane, −(1252.09 ± 0.20). Enthalpies of formation in the liquid state are derived. A comparison of the enthalpies of combustion of the alkyl cyclopentanes and alkyl cyclohexanes is made.

Enthalpy of formation of uranium sesquicarbide

The enthalpy of formation of uranium sesquicarbide has been determined by means of oxygen bomb calorimetry and found to be ΔH f o(U 2C 3, 298.15 K) = −(43.4 ± 1.8) kcal mol −1.

Enthalpies of formation of triuranium octaoxide and uranium dioxide

The enthalpies of formation of triuranium octaoxide and uranium dioxide have been determined by oxygen bomb calorimetry and found to be ΔH f o (U 3O 8, 298.15 K) = −(854.4±0.6) kcal mol −1 and ΔH f o (UO 2, 298.15 K) = −259.3±0.2) kcal mol −1.

Enthalpy of formation of europium monoxide

The enthalpy of formation of europium monoxide (EuO 1.02) has been determined by means of oxygen bomb calorimetry and found to be ΔH f o(298.15 K, EuO 1.02) = − (143.3 ± 0.5) kcal mol −1. A value of ΔH f o(298.15 K, EuO) = − (135.0 ± 1.3) kcal mol −1 was derived.

The calorimetry of combustions and related reactions: inorganic reactions

Abstract