You have the following substances: \(NH_3\), \(O_2\), \(Pt\) and \(H_2O\). Arrange the following equations for the preparation of \(N_2O\) from these compounds.
A. \(NH_4NO_3 (aq) \underset{\text{at room temperature}}{\overset{\text{vacc. evapouration}}{\longrightarrow}}NH_4NO_3 \overset{523 k}{\longrightarrow}N_2O (g) + 2H_2O\)
B. \(NH_3 (g) + HNO_3 (aq) \longrightarrow NH_4NO_3 (aq)\)
C. \(3NO_2 (g) + H_2O (l) \longrightarrow 2HNO_3 (aq) + NO(g)\)
D. \(2NO (g) + O_2 (g) \longrightarrow 2NO_2 (g)\)
E. \(4NH_3 (g) + 5O_2 (g) \underset{1100 K}{\overset{Pt}{\longrightarrow}} 4NO (g) + 6H_2O (l)\)
Choose the correct answers from the options given below:
Answer & explanation
Correct answer: option 1
The correct answer is option 1. E, D, C, B, A.
Let us go through the detailed explanation of how each step contributes to the preparation of nitrous oxide (\(N_2O\)) from the given starting materials: \(NH_3\) (ammonia), \(O_2\) (oxygen), \(Pt\) (platinum catalyst), and \(H_2O\) (water).
The process of synthesizing \(N_2O\) from these materials involves several intermediate steps. The overall goal is to transform ammonia (\(NH_3\)) into nitrous oxide (\(N_2O\)) through a series of reactions involving the formation of nitric oxide (\(NO\)), nitrogen dioxide (\(NO_2\)), nitric acid (\(HNO_3\)), and ammonium nitrate (\(NH_4NO_3\)).
Step-by-Step Breakdown
Step 1: Oxidation of Ammonia to Nitric Oxide (NO)
Reaction: \(4NH_3 (g) + 5O_2 (g) \overset{\text{Pt}, 1100 K}{\longrightarrow} 4NO (g) + 6H_2O (l)\)
In this step, ammonia (\(NH_3\)) is oxidized by oxygen (\(O_2\)) in the presence of a platinum catalyst at a high temperature (1100 K). The reaction produces nitrogen monoxide (\(NO\)) and water (\(H_2O\)). This is a key step in the Ostwald process, which is used industrially to produce nitric acid. However, here, it's the starting point for our \(N_2O\) synthesis.
Step 2: Oxidation of Nitric Oxide to Nitrogen Dioxide (NO_2)
\(2NO (g) + O_2 (g) \longrightarrow 2NO_2 (g)\)
The nitric oxide (\(NO\)) produced in Step 1 is further oxidized by oxygen to form nitrogen dioxide (\(NO_2\)). This step is crucial because \(NO_2\) is a precursor for nitric acid, which is needed to form ammonium nitrate.
Step 3: Formation of Nitric Acid (HNO_3)
\(3NO_2 (g) + H_2O (l) \longrightarrow 2HNO_3 (aq) + NO(g)\)
Nitrogen dioxide (\(NO_2\)) reacts with water (\(H_2O\)) to produce nitric acid (\(HNO_3\)) and nitrogen monoxide (\(NO\)).The nitric acid formed is needed in the next step to react with ammonia and form ammonium nitrate.
Step 4: Formation of Ammonium Nitrate (NH_4NO_3)
\(NH_3 (g) + HNO_3 (aq) \longrightarrow NH_4NO_3 (aq)\)
Ammonia (\(NH_3\)) reacts with the nitric acid (\(HNO_3\)) produced in Step 3 to form ammonium nitrate (\(NH_4NO_3\)). Ammonium nitrate is a key intermediate because it decomposes upon heating to produce nitrous oxide.
Step 5: Decomposition of Ammonium Nitrate to Nitrous Oxide (N_2O
\(NH_4NO_3 (aq) \underset{\text{room temperature}}{\overset{\text{vacc. evap.}}{\longrightarrow}} NH_4NO_3 (s) \overset{523 K}{\longrightarrow} N_2O (g) + 2H_2O\)
Ammonium nitrate (\(NH_4NO_3\)) is first concentrated and then heated to about 523 K (250°C). At this temperature, it decomposes to form nitrous oxide (\(N_2O\)) and water vapor (\(H_2O\)). This final step completes the synthesis of nitrous oxide.
Summary of the Sequence
The correct sequence of reactions to prepare \(N_2O\) from \(NH_3\), \(O_2\), \(Pt\), and \(H_2O\) is:
Statement E: Ammonia is oxidized to nitric oxide using oxygen and a platinum catalyst.
Statement D: Nitric oxide is further oxidized to nitrogen dioxide.
Statement C: Nitrogen dioxide reacts with water to form nitric acid.
Statement B: Ammonia reacts with nitric acid to produce ammonium nitrate.
Statement A: Ammonium nitrate is heated to decompose into nitrous oxide and water.
Thus, the correct sequence is E, D, C, B, A.