Oxidation-Reduction Reactions Launch the Space Shuttle

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Launching into space a vehicle that weighs millions of pounds ... 27.5 feet in diameter). Right solid rocket booster. Space shuttle main engines. 78.06 feet. Space ...

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CHEMISTRY IN FOCUS Oxidation–Reduction Reactions Launch the Space Shuttle Launching into space a vehicle that weighs millions of pounds requires unimaginable quantities of energy—all furnished by oxidation–reduction reactions. Notice from Figure 7.8 that three cylindrical objects are attached to the shuttle orbiter. In the center is a tank about 28 feet in diameter and 154 feet long that contains liquid oxygen and liquid hydrogen (in separate compartments). These fuels are fed to the orbiter’s rocket engines, where they react to form water and release a huge quantity of energy.

nium perchlorate (NH4ClO4) and powdered aluminum mixed with a binder (“glue”). Because the rockets are so large, they are built in segments and assembled at the launch site as shown in Figure 7.9. Each segment is filled with the syrupy propellant (Figure 7.10), which then solidifies to a consistency much like that of a hard rubber eraser. The oxidation–reduction reaction between the ammonium perchlorate and the aluminum is represented as follows:

2H2  O2 S 2H2O  energy

3NH4ClO4 1s2  3Al1s2 S Al2O3 1s2  AlCl3 1s2  3NO1g2  6H2O1g2  energy

Note that we can recognize this reaction as an oxidation–reduction reaction because O2 is a reactant. Two solid-fuel rockets 12 feet in diameter and 150 feet long are also attached to the orbiter. Each rocket contains 1.1 million pounds of fuel: ammo-

It produces temperatures of about 5700 F and 3.3 million pounds of thrust in each rocket. Thus we can see that oxidation–reduction reactions furnish the energy to launch the space shuttle.

External fuel tank (153.8 feet long, 27.5 feet in diameter) Solid booster Left solid rocket booster Orbiter vehicle

Right solid rocket booster Space shuttle main engines

78.06 feet Space shuttle Discovery stacked for launch Figure 7.8 For launch, the space shuttle orbiter is attached to two solidfuel rockets (left and right) and a fuel tank (center) that supplies hydrogen and oxygen to the orbiter’s engines. (Reprinted with permission from Chemical and Engineering News, September 19, 1988. Copyright © 1988 American Chemical Society.)

Aft field joint (point of failure in Challenger's right booster) Solid propellant

149.16 feet long, 12.17 feet in diameter Figure 7.9 The solid-fuel rockets are assembled from segments to make loading the fuel more convenient. (Reprinted with permission from Chemical and Engineering News, September 19, 1988. Copyright © 1988 American Chemical Society.)

Figure 7.10 A rocket segment being filled with the propellant mixture.

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