Accession Number : AD0239086

Title :   The Properties of Boron Compounds.

Descriptive Note : Rept. on aviation fuels,

Corporate Author : NATIONAL BUREAU OF STANDARDS GAITHERSBURG MD

Personal Author(s) : West, Estal D.

Report Date : MAY 1960

Pagination or Media Count : 17

Abstract : HEATS OF FORMATION OF THE METABORIC ACIDS, by Marthada V. Kilday and Edward J. Prosen: Three crystalline forms of metaboric acid exist: HBO2(C,I), HBO2(C,II), and HBO2(C,III). Methods of preparing and identifying these 3 crystals and crystals of orthoboric acid H3BO3 are described. The heats of formation of the 3 forms of metaboric acid relative of that of orthoboric acid have been determined by measuring heats of solution of each of the 4 crystals in water and in sodium hydroxide solution. Taking the heat of formation of orthboric acid as Hf(25 C) = 262.16 + or - 0.32 kcal/mole, the heats of formation of the forms of metaboric acid were found to be HBO2(C,I), < Hf(25 C) = 192.56 + or - 0.40 kcal/mole; HBO2(C,II), < Hf(25 C) = 190.6 + or - 0.5 kcal/mole; HBO2(C,III) / Hf(25 C) = -190.0 + or - 1.0 kcal/mole. DECOMPOSITION PRESSURES OF BORIC ACID, by Edward J. Prosen: Decomposition pressure measurements were made on the system H3BO3(C) = H2O(g) + HBO2(C,X), where the metaboric acid HBO2 was in the form of HBO2(C2,I), HBO2(C,II), or HBO2(C,III). The results on crystals II and III confirm the data obtained by previous investigators. No previous data existed on crystal I, the most stable form of metaboric acid. From these measurements, heats of formation, free energies of formation, and entropies are derived. (Author)

Descriptors :   *BORIC ACID, CRYSTALS, HEAT OF FORMATION, BORON COMPOUNDS, THERMODYNAMICS, DECOMPOSITION, PRESSURE, MEASUREMENT, AVIATION FUELS.

Distribution Statement : APPROVED FOR PUBLIC RELEASE