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: Given the following thermochemical data:Fe2O3(s) + CO(g) → 2 FeO(s) + CO2(g)         ∆H = −2.9 kJFe(s) + CO2(g) → FeO(s) + CO(g)                  ∆H = 11.3 kJdetermine ∆H for the following reaction:Fe2O3(s) + 3 CO(g) −−→ 2 Fe(s) + 3 CO2(g)(A) 8.4 kJ (B) -8.4 kJ (C) -25.5 kJ (D) 25.5 kJ (E) -19.7 kJ

Problem

Given the following thermochemical data:

Fe2O3(s) + CO(g) → 2 FeO(s) + CO2(g)         ∆H = −2.9 kJ

Fe(s) + CO2(g) → FeO(s) + CO(g)                  ∆H = 11.3 kJ

determine ∆H for the following reaction:

Fe2O3(s) + 3 CO(g) −−→ 2 Fe(s) + 3 CO2(g)

(A) 8.4 kJ 

(B) -8.4 kJ 

(C) -25.5 kJ 

(D) 25.5 kJ 

(E) -19.7 kJ

Solution

Apply Hess’s Law to determine the ΔH of the overall reaction where we have to get the sum of ΔH of the elementary reactions given

  • The overall reaction appears to be:

Fe2O3(s) + 3 CO(g)  2 Fe(s) + 3 CO2(g)

  • And the elementary reactions are:

Fe2O3(s) + CO(g)  2 FeO(s) + CO2(g)         ∆H = −2.9 kJ

Fe(s) + CO2(g)  FeO(s) + CO(g)                  ∆H = 11.3 kJ

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