---
title: "Hydrazine, \\(\\text{N}_2\\text{H}_4\\), is an inorganic compound used as a rocket propellant. A student investigates the synthesis of liquid hydrazine from gaseous ammonia and oxygen gas according to the following reaction:  \\[ 2\\,\\text{NH}_3(g) + \\frac{1}{2}\\,\\text{O}_2(g) \\rightarrow \\text{N}_2\\text{H}_4(l) + \\text{H}_2\\text{O}(l) \\]  The student finds the following thermochemical data:  \\[ \\text{N}_2\\text{H}_4(l) + \\text{O}_2(g) \\rightarrow \\text{N}_2(g) + 2\\,\\text{H}_2\\text{O}(l) \\quad \\Delta H^\\circ = -622\\text{ kJ/mol}_{\\text{rxn}} \\]  \\[ \\text{N}_2(g) + 3\\,\\text{H}_2(g) \\rightarrow 2\\,\\text{NH}_3(g) \\quad \\Delta H^\\circ = -92\\text{ kJ/mol}_{\\text{rxn}} \\]  \\[ 2\\,\\text{H}_2(g) + \\text{O}_2(g) \\rightarrow 2\\,\\text{H}_2\\text{O}(l) \\quad \\Delta H^\\circ = -572\\text{ kJ/mol}_{\\text{rxn}} \\]  Based on the data provided, what is the value of \\(\\Delta H^\\circ\\) for the synthesis reaction?"
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url: "https://nerd-notes.com/ubq/119826/"
date_modified: "2026-08-21T08:12:33+00:00"
---

# Hydrazine, \(\text{N}_2\text{H}_4\), is an inorganic compound used as a rocket propellant. A student investigates the synthesis of liquid hydrazine from gaseous ammonia and oxygen gas according to the following reaction:

\[ 2\,\text{NH}_3(g) + \frac{1}{2}\,\text{O}_2(g) \rightarrow \text{N}_2\text{H}_4(l) + \text{H}_2\text{O}(l) \]

The student finds the following thermochemical data:

\[ \text{N}_2\text{H}_4(l) + \text{O}_2(g) \rightarrow \text{N}_2(g) + 2\,\text{H}_2\text{O}(l) \quad \Delta H^\circ = -622\text{ kJ/mol}_{\text{rxn}} \]

\[ \text{N}_2(g) + 3\,\text{H}_2(g) \rightarrow 2\,\text{NH}_3(g) \quad \Delta H^\circ = -92\text{ kJ/mol}_{\text{rxn}} \]

\[ 2\,\text{H}_2(g) + \text{O}_2(g) \rightarrow 2\,\text{H}_2\text{O}(l) \quad \Delta H^\circ = -572\text{ kJ/mol}_{\text{rxn}} \]

Based on the data provided, what is the value of \(\Delta H^\circ\) for the synthesis reaction?

Hydrazine, \(\text{N}_2\text{H}_4\), is an inorganic compound used as a rocket propellant. A student investigates the synthesis of liquid hydrazine from gaseous ammonia and oxygen gas according to the following reaction:

\[ 2\,\text{NH}_3(g) + \frac{1}{2}\,\text{O}_2(g) \rightarrow \text{N}_2\text{H}_4(l) + \text{H}_2\text{O}(l) \]

The student finds the following thermochemical data:

\[ \text{N}_2\text{H}_4(l) + \text{O}_2(g) \rightarrow \text{N}_2(g) + 2\,\text{H}_2\text{O}(l) \quad \Delta H^\circ = -622\text{ kJ/mol}_{\text{rxn}} \]

\[ \text{N}_2(g) + 3\,\text{H}_2(g) \rightarrow 2\,\text{NH}_3(g) \quad \Delta H^\circ = -92\text{ kJ/mol}_{\text{rxn}} \]

\[ 2\,\text{H}_2(g) + \text{O}_2(g) \rightarrow 2\,\text{H}_2\text{O}(l) \quad \Delta H^\circ = -572\text{ kJ/mol}_{\text{rxn}} \]

Based on the data provided, what is the value of \(\Delta H^\circ\) for the synthesis reaction?

- **A.** \(-144\text{ kJ/mol}_{\text{rxn}}\)
- **B.** \(+142\text{ kJ/mol}_{\text{rxn}}\)
- **C.** \(+428\text{ kJ/mol}_{\text{rxn}}\)
- **D.** \(+1572\text{ kJ/mol}_{\text{rxn}}\)

*The answer key and step-by-step explanation are available to logged-in users at https://nerd-notes.com/ubq/119826/*