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

Solution: The following sequence of reactions occurs in the commercial production of aqueous nitric acid:4NH3(g) + 5O2(g) ⟶ 4NO(g) + 6H2O(l)           ΔH = −907 kJ2NO(g) + O2(g) ⟶ 2NO2(g)                      

Solution: The following sequence of reactions occurs in the commercial production of aqueous nitric acid:4NH3(g) + 5O2(g) ⟶ 4NO(g) + 6H2O(l)           ΔH = −907 kJ2NO(g) + O2(g) ⟶ 2NO2(g)                      

Problem

The following sequence of reactions occurs in the commercial production of aqueous nitric acid:

4NH3(g) + 5O2(g) ⟶ 4NO(g) + 6H2O(l)           ΔH = −907 kJ
2NO(g) + O2(g) ⟶ 2NO2(g)                             ΔH = −113 kJ
3NO2 + H2O(l) ⟶ 2HNO3(aq) + NO(g)            ΔH = −139 kJ

Determine the total energy change for the production of one mole of aqueous nitric acid by this process.

Solution

To find the ΔHrxn, we need to combine the three reactions where we should be getting HNO3 as product

However, the problem is asking for the energy needed to produce 1 mole of HNO3, and in the given 3rd reaction, we have 2 moles of HNO3

We will be dividing the final ΔH calculated by 2 to get the energy needed for every 1 mol HNO3 produced

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