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: Diamond and graphite are two crystalline forms of carbon. At 1 atm and 25°C, diamond changes to graphite so slowly that the enthalpy change of the process must be obtained indirectly. Using equations from the list below, determine ΔH  for C(diamond) ⟶ C(graphite)
(1) C(diamond) + O2(g) ⟶ CO2(g)          ΔH = −395.4 kJ
(2) 2CO2(g) ⟶ 2CO(g) + O2(g)              Δ H = 566.0 kJ
(3) C(graphite) + O2(g) ⟶ CO2(g)          Δ H = −393.5 kJ
(4) 2CO(g) ⟶ C(graphite) + CO2(g)      ΔH = −172.5 kJ

Solution: Diamond and graphite are two crystalline forms of carbon. At 1 atm and 25°C, diamond changes to graphite so slowly that the enthalpy change of the process must be obtained indirectly. Using equations

Problem

Diamond and graphite are two crystalline forms of carbon. At 1 atm and 25°C, diamond changes to graphite so slowly that the enthalpy change of the process must be obtained indirectly. Using equations from the list below, determine ΔH  for 

C(diamond) ⟶ C(graphite)
(1) C(diamond) + O2(g) ⟶ CO2(g)          ΔH = −395.4 kJ
(2) 2CO2(g) ⟶ 2CO(g) + O2(g)              Δ H = 566.0 kJ
(3) C(graphite) + O2(g) ⟶ CO2(g)          Δ H = −393.5 kJ
(4) 2CO(g) ⟶ C(graphite) + CO2(g)      ΔH = −172.5 kJ