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The reusable booster rockets of the space shuttle use a mixture of aluminum and ammonium perchlorate as fuel. A possible reaction is: 3Al+3NH_4ClO_4→Al_2 O_3 +AlCl_3

​ +3NO+6H _2O. Calculate the change in enthalpy for this reaction.
a. ΔH>0
b. ΔH<0
c. ΔH=0
d. The change in enthalpy cannot be determined.

1 Answer

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Final answer:

Without specific enthalpies of formation data, the change in enthalpy for the space shuttle's fuel reaction cannot be determined; therefore, the answer is d. The change in enthalpy cannot be determined.

Step-by-step explanation:

The change in enthalpy (ΔH) for the chemical reaction of aluminum and ammonium perchlorate in reusable booster rockets such as those used on the space shuttle can be calculated using thermodynamic data, which is typically found in standard reference tables. As the reaction provided is a typical combustion reaction, it's expected to release energy. Unfortunately, without the specific enthalpies of formation for the reactants and products, the exact value of ΔH cannot be determined from the given information alone.

Therefore, the correct answer is d. The change in enthalpy cannot be determined with the information provided. To calculate ΔH for a reaction, one needs the enthalpies of formation for all reactants and products to apply Hess's Law or the standard enthalpy change equation. Since the products have a lower enthalpy than the reactants, the change in enthalpy for this reaction (ΔH) is negative, and the correct answer is b. ΔH<0.

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