Day 22 Podia Question

Podia Question

Ammonium nitrate is an important fertilizer that supplies nitrogen to crops. It also can be used as an explosive to remove tree stumps from farm fields or in terrorist bombings. There are two reactions that can occur to produce the explosive effect. At lower temperatures ammonium nitrate decomposes to form dinitrogen monoxide and water vapor, but at higher temperatures it decomposes explosively to form nitrogen, water vapor, and oxygen. The reaction equations and thermodynamic parameters at 298 K are

(1) NH4NO3(s) ⇌ N2O(g) + 2 H2O(g)                 ΔrH° = −36.026 kJ/mol ΔrS° = 446.42 J K−1 mol−1

(2) NH4NO3(s) ⇌ N2(g) + ½ O2(g) + 2 H2O(g)   ΔrH° = −118.076 kJ/mol ΔrS° = 520.749 J K−1 mol−1

a) Which of the reactions is(are) product-favored at room temperature? Which of the reactions is(are) product-favored at 1000 K? Explain briefly.

b) Is there a temperature below which one of the reactions is more product-favored and above which the other reaction is more product-favored? If there is such a temperature for these two reactions, determine what that temperature is.

c) Given your results, propose a scientific explanation of the fact that nitrogen and oxygen are produced explosively at higher temperatures but dinitrogen monoxide is produced at lower temperatures.

Two days before the next whole-class session, this Podia question will become live on Podia, where you can submit your answer.

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Chemistry 109 Fall 2021 by John Moore, Jia Zhou, and Etienne Garand is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License, except where otherwise noted.