The space shuttle's solid rocket boosters use ammonium perchlorate and aluminum to create an explosive reaction. The unbalanced reaction can be seen below. NH4ClO4 (s) + Al (s) yields Al2O3 (g) + HCl (g) + N2 (g) + H2O (g) Which of the following statements correctly describes this reaction?

1. Chlorine is being oxidized

2. aluminum is gaining electrons

3. nitrogen is being reduced

4. aluminum is a reducing agent.

Here we have to choose the statement which correctly describe the reaction NH₄ClO₄ (s) + Al (s) → Al₂O₃ (g) + HCl (g) + N₂ (g) + H₂O (g).

The correct statement for the reaction:

NH₄ClO₄ (s) + Al (s) → Al₂O₃ (g) + HCl (g) + N₂ (g) + H₂O (g) is 4. aluminum is reducing agent.

The reaction between ammonium perchlorate and aluminium metal as given:

NH₄ClO₄ (s) + Al (s) → Al₂O₃ (g) + HCl (g) + N₂ (g) + H₂O (g)

In this reaction the change of oxidation state of each element is:

a) nitrogen (N) from - 3 to 0 thus oxidation. Thus nitrogen is oxidized in this reaction.

b) chlorine (Cl) from + 7 to - 1 thus reduction. Thus chlorine is reduced in this reaction.

c) Aluminum (Al) from 0 to + 3 state thus oxidation. Al is loosing electrons; Thus aluminum is being oxidized.

We know the gaining of electron is a reducing process and the compound itself is an oxidizing agent, whereas the loosing of electrons is a oxidation process and the compound itself is an reducing agent.

Thus aluminum is a reducing agent in this reaction.