Aluminium containers are frequently used to transport trioxonitrate (V) acid because aluminium

Analysis

The question asks why aluminium is the preferred material for transporting trioxonitrate(V) acid (also known as nitric acid, $HNO_3$). We need to look at the chemical interaction between aluminium and concentrated nitric acid.

Concept Explanation

In chemistry, we often expect metals to react with acids to produce hydrogen gas and a salt. However, concentrated trioxonitrate(V) acid acts as a powerful oxidizing agent.

When aluminium comes into contact with concentrated $HNO_3$, it undergoes a process called passivation. The acid reacts with the surface of the aluminium to form a thin, non-porous, and highly unreactive layer of aluminium oxide ($Al_2O_3$). This oxide layer acts as a protective "skin" that prevents the acid from reaching the underlying metal, effectively stopping any further reaction.

Step-by-Step Solution

1. Understand the reaction: Aluminium is a reactive metal, but its reactivity is modified by the formation of an oxide layer.
2. Evaluate the options: • A (Silvery-white appearance): This is a physical property, not a chemical reason for stability. • B (Low density): While true, this makes it convenient for transport, but it doesn't explain why it doesn't dissolve in the acid. • C (Does not react with the acid): Due to the passivation layer formed, the bulk of the aluminium remains protected and does not react with the acid. This makes it safe for storage and transport. • D (Does not corrode): This is technically incorrect; aluminium does corrode (oxidize), but the product of that corrosion (the oxide layer) is what protects the metal.

Conclusion

Because the aluminium becomes "passive" due to the protective oxide layer, it effectively does not react with the concentrated acid. Therefore, it is safe to use for transport.

Exam Tip: Remember that concentrated nitric acid renders iron and aluminium "passive." Don't be fooled into thinking they are naturally unreactive metals like gold or platinum; they are simply protected by their own oxide coating!