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General Identification of Hydrogen Peroxide

hydrogen peroxide Propulsion

Part of the Hydrogen Peroxide Propulsion Guide The physical classifications under general identification are those properties that are used to identify hydrogen peroxide and its physical state.

Molecular Weight of Hydrogen Peroxide

General Properties of Hydrogen PeroxideThe molecular weight of hydrogen peroxide was experimentally determined by freezing point depression (Ref. 2.1 and 2.2) and vapor density (Ref. 2.3) measurements. The results of these studies are comparable to the value of 34.016 calculated from the International Atomic Weights. The mole percent and apparent molecular weight as a function of weight percent H2O2 for various aqueous solutions of H2O2, as shown in Fig. 2.1, were calculated from the molecular weights of H2O and H2O2 based on the International Atomic Weights.

Freezing Point Hydrogen Peroxide

The determination of freezing and melting points of H2O2-H2O solutions is relatively difficult because of the large degree of supercooling possible with these solutions. In addition, phase equilibrium measurements (Ref. 2.2) have indicated that solid solutions are not formed in the solidification of concentrated (greater than 65 w/o H2O2) aqueous solutions of H2O2; instead, the solid consists of crystals of H2O2 with occluded mother liquid. Thus, the range of temperatures over which the material melts or freezes is a function of the crystallization pattern of the H2O2. The freezing point of "100 percent" H2O2 has been reported as -0.61 c (31.17 F), -0.43 C (31.23 F),and -0.41 C (31.26 F) in Ref. 2.2, 2.4, and 2.5, respectively. Based on a reported sample purity of 99.97 m/o H2O2, the freezing point determination of Ref. 2.4 was selected as representative of 100 percent H2O2 . Measurements of the freezing points of aqueous solutions of H2O2 (Ref. 2.2) indicate eutectics at 45.2 w/o H2O2 and -52.4 C (-62.3 F), and at 61.2 w/o H2O2 and -56.5 C (-69.7 F). The results of these measurements, which are graphically illustrated in Fig. 2.2 and 2.2a, represent the temperatures at which 20 to 30 percent of th liquid had solidified. Experimental melting point studies (Ref. 2.6), based on observation of the temperature at which melting was complete, resulted in slightly higher melting temperatures for concentrations above 60 w/o H2O2.

A variety of experimental studies have produced no significantly effective freezing point depressants for propellant-grade H2O2 solutions. These studies, described in detail in Ref. 2.3 and 2.6 through 2.9, have shown that many additives will form, unstable or shock-sensitive mixtures with H2O2.

concentration and apparent molecular weight of hydrogen peroxide


freezing point of hydrogen peroxide


critical temperature of hydrogen peroxide

Triple Point of Hydrogen Peroxide

The triple point of 99.97 m/o H2O2 was estimated as 272.74 K (-0.42 C or 31.24 F) from experimental heat of fusion studies (Ref. 2.5). Although no vapor pressure measurements have been made on solid H2O2, the vapor pressure at the triple point has been calculated (Ref. 2.10) as 0.26 mm 1g (0.005 psia).

Normal Boiling Point of Hydrogen Peroxide

The normal boiling points of propellant-grade H2O2 solutions have not been experimentally determined by conventional means since these points are in a temperature region where thermal decomposition of the H2O2 is significant. The normal boiling pints listed in Table 2.1 and Fig. 2.3 for propellant-grade H2O2-H2O solutions represent extrapolations of the vapor pressure data of Section to 1 atmosphere of pressure. Other references (i.e., Ref. 2.11 and 2.12) give very similar boiling points even though these temperatures were calculated from extrapolations of different individual sets of vapor pressure data. The correlation of these individual sets of data, which results in the newly calculated normal boiling points, is discussed in Section

Critical Properties of Hydrogen Peroxide

There has been no experimental determinations of critical properties of H2O2 since the compound undergoes extensive decomposition before the critical temperature is achieved. However, because this property is of academic interest, the critical temperature has been estimated by assuming that the critical temperature/boiling point ratio of H2O2 is equal to that of water. Based on this technique, a critical temperature (Tc) of 458.8 C (857.8 F) has been reported for 100 w/o H2O2 (Ref. 2.11); another Tc value of 457 C (855 F) for 100 w/o H2O2, which was alluded to in Ref. 2.12, was reported in Ref. 2.10. Using a vapor pressure equation established in Ref. 2.12, the critical pressure, Pc was calculated (Ref. 2.10) as 214 atmospheres (3140 psia) at the latter Tc. Using the estimated boiling point given in Table 2.1 and correlation technique described above, a Tc of 733 1K (460 C, 860 F) is recommended for 100 w/o H2O2. An estimation technique suggested in Ref. 2.12 (Pc/Tc is equivalent for both H2O2 and H2O) resulted in a calculated and recommended Pc of 247 atmospheres (3630 psia) for 100 w/o H2O2 using the Tc value of 733 K. Pseudo critical constants were calculated for the propellant-grade H2O2-H2O solutions through the use of Kay's method (Ref. 2.13); the results of these calculations are shown in Table 2.1 and in Fig. 2.3. Adiabatic compressibility of propellant grade hydrogen peroxide   Adiabatic compressibility of propellant grade hydrogen peroxide   vapor pressure of propellant grade hydrogen peroxide water solutions   Vapor pressure of propellant grade hydrogen peroxide water solutions   Vapor composition over hydrogen peroxide water solutions Vapor liquid equilibrium for the hydrogen peroxide water system Image cc Flickr via NASA

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