Problem 22 - Chemistry: The Central Science

Question

Hydrazine \(\left(\mathrm{N}_{2} \mathrm{H}_{4}\right)\) and dinitrogen tetroxide \(\left(\mathrm{N}_{2} \mathrm{O}_{4}\right)\) form a self-igniting mixture that has been used as a rocket propellant. The reaction products are \(\mathrm{N}_{2}\) and \(\mathrm{H}_{2} \mathrm{O}\). (a) Write a balanced chemical equation for this reaction. (b) What is being oxidized, and what is being reduced? (c) Which substance serves as the reducing agent and which as the oxidizing agent?

Step-by-Step Solution

Answer

(a) The balanced chemical equation for the reaction is: \[ N_{2}H_{4} + 2N_{2}O_{4} \rightarrow 3N_{2} + 4H_{2}O \] (b) Nitrogen in hydrazine is being oxidized, while nitrogen in dinitrogen tetroxide is being reduced. (c) Hydrazine \(N_{2}H_{4}\) serves as the reducing agent, and dinitrogen tetroxide \(N_{2}O_{4}\) serves as the oxidizing agent.

Step 1: Write the unbalanced chemical equation

The unbalanced chemical equation shows the reactants and products. In this case, they are hydrazine, dinitrogen tetroxide, nitrogen gas, and water: \[ N_{2}H_{4} + N_{2}O_{4} \rightarrow N_{2} + H_{2}O \]

Step 2: Balance the chemical equation

To balance the chemical equation, we will adjust the coefficients in front of each molecule to ensure the same number of atoms on both sides of the equation. The balanced chemical equation is: \[ N_{2}H_{4} + 2N_{2}O_{4} \rightarrow 3N_{2} + 4H_{2}O \] Part B: Identify the substances being oxidized and reduced

Step 3: Determine the oxidation states of each atom in the reactants and products

The oxidation states for each element in the reactants and products are: Hydrazine (N2H4): N: -2 (each) H: +1 (each) Dinitrogen Tetroxide (N2O4): N: +4 (each) O: -2 (each) Nitrogen Gas (N2): N: 0 Water (H2O): H: +1 (each) O: -2

Step 4: Identify the substances being oxidized and reduced

Compare the oxidation states of elements in the reactants to those in the products: - Nitrogen in hydrazine (going from -2 to 0): Oxidized - Nitrogen in dinitrogen tetroxide (going from +4 to 0): Reduced Part C: Determine the reducing agent and the oxidizing agent

Step 5: Identify the reducing agent and the oxidizing agent

Since hydrazine's nitrogen is being oxidized, hydrazine (N2H4) is the reducing agent. Similarly, since dinitrogen tetroxide's nitrogen is being reduced, dinitrogen tetroxide (N2O4) is the oxidizing agent.