The space shuttle orbiter utilizes the oxidation of...

The space shuttle orbiter utilizes the oxidation of methylhydrazine by dinitrogen tetroxide for propulsion: $4 \mathrm{~N}_{2} \mathrm{H}_{3} \mathrm{CH}_{3}(l)+5 \mathrm{~N}_{2} \mathrm{O}_{4}(l) \longrightarrow 12 \mathrm{H}_{2} \mathrm{O}(g)+9 \mathrm{~N}_{2}(g)+4 \mathrm{CO}_{2}(g)$ Calculate $\Delta H^{\circ}$ for this reaction.

The space shuttle orbiter utilizes the oxidation of methylhydrazine by dinitrogen tetroxide for propulsion:
$4 \mathrm{~N}_{2} \mathrm{H}_{3} \mathrm{CH}_{3}(l)+5 \mathrm{~N}_{2} \mathrm{O}_{4}(l) \longrightarrow 12 \mathrm{H}_{2} \mathrm{O}(g)+9 \mathrm{~N}_{2}(g)+4 \mathrm{CO}_{2}(g)$
Calculate $\Delta H^{\circ}$ for this reaction.

Labs

Want to see this concept in action?

NEW

Explore this concept interactively to see how it behaves as you change inputs.

View Labs

Key Concepts

Standard Enthalpies of Formation

These are the enthalpy changes that occur when one mole of a compound is formed from its elements in their most stable forms under standard conditions. They provide the baseline data needed to compute the enthalpy change for a reaction by accounting for the energy required to form or break chemical bonds.

Standard Enthalpy Change (?H°)

This is the measure of heat absorbed or released during a reaction under standard conditions (usually 1 atm pressure and 25°C). It is calculated by subtracting the sum of the standard enthalpies of formation of the reactants from that of the products, considering their stoichiometric coefficients.

Hess's Law

Hess's Law asserts that the enthalpy change for a reaction is independent of the pathway between the initial and final states. This principle allows one to calculate the overall reaction enthalpy by summing the enthalpy changes of individual steps, particularly by using standard enthalpies of formation.

Stoichiometry

Stoichiometry involves the quantitative relationships dictated by the balanced chemical equation. Correct use of stoichiometric coefficients is essential in scaling the standard enthalpies of formation properly for all reactants and products when calculating the overall reaction enthalpy.

Transcript

Please give Ace some feedback