# Thermochemical Equations

A thermochemical equation is a stoichiometric question that now involves the variable of ΔHReaction. Instead of doing a mole to mole comparison we will now do a mole to ΔH comparison.

## Enthalpy and Chemical Reactions

Concept: Understanding Thermochemical Equations

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##### Video Transcript

Welcome back, guys. In this new video, we're going to take the concepts we learned about thermal chemistry and apply it to an older concept, stoichiometry.
Now, what we had to learn about the stoichiometric chart, we're going to have to continue to apply here. But now we're going to incorporate delta H of reactions. We're going to say a thermal chemical equation is an equation, a balanced equation, that contains our heat of reaction that's just delta H of reaction.

Example: Iron is reacts with oxygen according to the following equation at around 2000oC.  (0:35 – 4:10)

4 Fe (s)  +  3 O­2 (g)  → 2 Fe2O3 (s)

ΔHo = + 65.2 kJ/mol

Calculate the amount of grams of iron (III) oxide, Fe2O3, produced from the absorption of 4.82 x 109 J.

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Problem: Nitromethane (CH3NO2), sometimes used as a fuel for drag racing, burns according to the following reaction: 4 CH3NO2 (l) + 7 O2 (g) -----> 4 CO2 (g) + 6 H2O (g) + 4 NO2 (g) ?H = ? 2441.6 kJ How much heat is released by burning 125.0 g of nitromethane (MW: 61.044 g/mol)?

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