Question

The space shuttle orbiter utilizes the oxidation of methylhydrazine by dinitrogen tetroxide for propulsion: 4 N₂H₃CH₃(l) + 5 N₂O₄(l) -> 12 H₂O(g) + 9 N₂(g) + 4 CO₂(g) Calculate ΔH° for this reaction.

Answer 1

To calculate ΔH° for the given reaction, use the standard enthalpies of formation of the products and reactants.

To calculate ΔH° for the given reaction, we need to use the standard enthalpies of formation of the products and reactants.

The standard enthalpy of formation for a compound is the change in enthalpy that occurs when one mole of the compound is formed from its elements in their standard states.

We can find the standard enthalpy of formation values in Appendix G. Now, for the given reaction: 4 N₂H₃CH₃(l) + 5 N₂O₄(l) -> 12 H₂O(g) + 9 N₂(g) + 4 CO₂(g)

We can use the standard enthalpies of formation to calculate the ΔH° as follows:

1. Calculate the ΔH° for the products: ΔH° = (12 * ΔH°(H₂O)) + (9 * ΔH°(N₂)) + (4 * ΔH°(CO₂))
2. Calculate the ΔH° for the reactants: ΔH° = (4 * ΔH°(N₂H₃CH₃)) + (5 * ΔH°(N₂O₄))
3. Calculate the overall ΔH° for the reaction: ΔH°(reaction) = ΔH°(products) - ΔH°(reactants)

Substitute the values from Appendix G to calculate ΔH° for the reaction.

Answer 2

To calculate the standard enthalpy change for the reaction of methylhydrazine with dinitrogen tetroxide, you use the standard enthalpy of formation values for each substance and apply them to the formula ΔH° = Σ(ΔH°f products) - Σ(ΔH°f reactants), considering the coefficients from the balanced equation.

Step-by-step explanation:

To calculate the standard enthalpy change (ΔH°) for the oxidation of methylhydrazine by dinitrogen tetroxide for propulsion, we would use the enthalpy of formation values for each of the reactants and products involved in the balanced chemical equation:

4 N₂H₃CH₃(l) + 5 N₂O₄(l) -> 12 H₂O(g) + 9 N₂(g) + 4 CO₂(g)

The ΔH° for a reaction can be calculated using the formula:

ΔH° = Σ(ΔH°f products) - Σ(ΔH°f reactants)

Where:

• 
  
• Σ(ΔH°f products) is the sum of the standard enthalpy of formation values of the products, each multiplied by its coefficient in the balanced equation.
• 
  
• Σ(ΔH°f reactants) is the sum of the standard enthalpy of formation values of the reactants, each multiplied by its coefficient.

Unfortunately, specific numerical values for the enthalpies of formation are not provided in the question, but they would typically be found in a table in the reference materials, such as Appendix G mentioned in the text. With those values, you could insert them into the formula and perform the calculation to find the ΔH° for the reaction.