Ch.6 - Thermochemistry WorksheetSee all chapters
All Chapters
Ch.1 - Intro to General Chemistry
Ch.2 - Atoms & Elements
Ch.3 - Chemical Reactions
BONUS: Lab Techniques and Procedures
BONUS: Mathematical Operations and Functions
Ch.4 - Chemical Quantities & Aqueous Reactions
Ch.5 - Gases
Ch.6 - Thermochemistry
Ch.7 - Quantum Mechanics
Ch.8 - Periodic Properties of the Elements
Ch.9 - Bonding & Molecular Structure
Ch.10 - Molecular Shapes & Valence Bond Theory
Ch.11 - Liquids, Solids & Intermolecular Forces
Ch.12 - Solutions
Ch.13 - Chemical Kinetics
Ch.14 - Chemical Equilibrium
Ch.15 - Acid and Base Equilibrium
Ch.16 - Aqueous Equilibrium
Ch. 17 - Chemical Thermodynamics
Ch.18 - Electrochemistry
Ch.19 - Nuclear Chemistry
Ch.20 - Organic Chemistry
Ch.22 - Chemistry of the Nonmetals
Ch.23 - Transition Metals and Coordination Compounds

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 #1: Understanding Thermochemical Equations

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 #1: 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. 

Practice: 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)?