The products of the thermal decomposition of ammonium trioxonitrate(v) are

Analysis

The question asks for the products formed when ammonium trioxonitrate(V), also known as ammonium nitrate ($NH_4NO_3$), undergoes thermal decomposition. This is a classic reaction in inorganic chemistry often tested in JAMB.

Concept

Thermal decomposition involves breaking down a chemical compound into simpler substances by heating it. Ammonium salts of oxidizing acids (like nitric acid) decompose differently than other ammonium salts. When ammonium nitrate is heated, it undergoes a redox reaction where the nitrogen in the ammonium ion ($NH_4^+$) is oxidized and the nitrogen in the nitrate ion ($NO_3^-$) is reduced.

Solution

1. Write the chemical formula: Ammonium trioxonitrate(V) is $NH_4NO_3$.
2. Write the balanced chemical equation: When $NH_4NO_3$ is heated gently, it decomposes into dinitrogen oxide (nitrous oxide) and water vapor.

3. Breakdown of the products: • $N_2O$ is Dinitrogen(I) oxide (also known as laughing gas). • $H_2O$ is water vapor.

Comparing this to your options:

• Option A: $N_2O$ and $H_2O$ (Matches our equation)
• Option B: $NO_2$ and $H_2O$ (This would be the product for a different nitrate decomposition)
• Option C: $N_2O$ and $O_2$ (Incorrect)
• Option D: $NO_3$ and $H_2O$ (Incorrect)

Conclusion

The thermal decomposition of ammonium trioxonitrate(V) yields dinitrogen oxide and water.

Exam Tip

Remember the "Ammonium Nitrate Rule":

• Gentle heating: $NH_4NO_3 \rightarrow N_2O + 2H_2O$
• Explosive/Strong heating: $2NH_4NO_3 \rightarrow 2N_2 + O_2 + 4H_2O$ If the question doesn't specify "explosive," always assume the standard decomposition into $N_2O$ and water.