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lecture5_new - 16.522, Space Propulsion Prof. Manuel...

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16.522, Space Propulsion Lecture 5 Prof. Manuel Martinez-Sanchez Page 1 of 12 16.522, Space Propulsion Prof. Manuel Martinez-Sanchez Lecture 5: Chemical Thrusters for In-Space Propulsion HYDRAZINE Hydrazine was first isolated by Curtius in 1887, and in 1907 a suitable synthetic method was developed by Raschig. Anhydrous hydrazine is a clear, colorless, hygroscopic liquid with an odor similar to that of ammonia. Anhydrous hydrazine is a strong reducing agent and a weak chemical base. Aqueous hydrazine shows both oxidizing and reducing properties. Although potential data show hydrazine to be a powerful oxidizing agent in acidic solutions, reactions with many reducing agents are so slow that only the most powerful ones reduce it quantitatively to ammonium ion. Hydrazine will react with carbon dioxide and oxygen in air. When hydrazine is exposed on a large surface to air, such as on rags, it may ignite spontaneously due to the evolution of heat caused by oxidation with atmospheric oxygen. A film of hydrazine in contact with metallic oxides and other oxidizing agents may ignite. Hydrazine is an endothermic compound and will decompose spontaneously in a similar way to hydrogen peroxide. The reaction of hydrazine with the oxides of copper, manganese, iron, silver, mercury, molybdenum, lead or chromium may be particularly violent. The spontaneous or artificially induced decomposition of hydrazine does not follow the reaction N 2 H 4 = N 2 +2H 2 , but a more exothermic one such as 2N 2 H 4 = 2NH 3 +N 2 +H 2 . SUMMARY AND CONTENTS PHYSICO-CHEMICAL PROPERTIES METRIC VALUE ENGLISH REFERENCE FIGURE Molecular Formula N 2 H 4 (1) Molecular Weight 32.04 (1) Freezing Point 1.5 C D 34.7 F D (6) Freezing Point Diagram with Additives 1 Boiling Point 113.5 C D 236.3 F D (10) 4 Critical Properties C P = 145 atm. c T =380C (716F) DD d c = 0.231 g/cc (5) (5) (5) 3 3 3 Density, liquid 1.0045 g cc @ 25 C D 8.482 lb gal @ 77 F D 2, 3 Density, vapor and liquid (5) 3 Vapor Pressure 14.38 mm @ 25 C D 0.0189 @ 77 F atm D (6) 4 Surface Tension 66.67 dynes/cm @ 25 C D 62.32 dynes/cm @ 35 C D .004568 lb ft @ 77 F D .004270 lb ft @ 95 F D (7) (9) Viscosity, liquid 0.90 centipoise @ 25 C D .000605 lb ft -sec @ 77 F D (11, 12) 5 Heat Flux at q ul / Pressure (8) 6 Heat Flux at q ul / Temperature (8) 7 Heat Flux at q ul / Velocity (8) 8
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16.522, Space Propulsion Lecture 5 Prof. Manuel Martinez-Sanchez Page 2 of 12 Heat of Fusion 3.025 kcal/mole @ 1.5 C D 37.51 Btu lb @ 34.7 D (6) Heat of Vaporization 9.600 kcal/mole @ 113.5 C D 54.0 Btu lb @ 236 F D (3) Heat Capacity (liquid) Temp. 23.62 cal/mole- C @ 25 C DD .737 Btu lb- F @ 77 F (6) 9 Heat of Combustion N 2 H 4 (l)+O 2 =N 2 +2H 2 O (l) 148.6 kcal/mole @ 25 C D 8.346 Btu lb@ 77 F D (20) Heats of Formation at 25 C (77 F) N 2 +2H 2 = N 2 H 4 (g) N 2 +2H 2 = N 2 H 4 (liq) N 2 +2H 2 +H 2 O = N 2 H 4 .H 2 O N 2 +2H 2 + aq = N 2 H 4 . aq 22.750 kcal/mole 11.999 kcal/mole 10.300 kcal/mole 8.140 kcal/mole 1278 Btu/lb 675 Btu/lb 579 Btu/lb 457 Btu/lb (20) (20) (20) (20) Index of Refraction, D 1.4644 @ 25 C (77 F) (9) Dielectric Constant 51.7 @ 25 C (77 F) (19) Electrical Conductivity -6 -1 31 0 o h m @ 2 5 C ( 7 7 F ) × (11) Flash Point (open cup) 52 C D 126 F D (18) Explosive Limits (in air, 1 atm.) 4.7% lower 100% upper (18) (18) B. Materials: The following table gives an evaluation of the compatibility data that
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This note was uploaded on 11/07/2011 for the course AERO 16.512 taught by Professor Manuelmartinez-sanchez during the Fall '05 term at MIT.

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lecture5_new - 16.522, Space Propulsion Prof. Manuel...

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