CH4 + 2O2 = CO2 + 2H2O - Reaction Thermochemistry Calculator

Thermodynamic Analysis Results

Chemical Equation:

Automatic Calculation (Database Values)

Thermodynamic Analysis
Property	Value	Interpretation
ΔH°_rxn Enthalpy Change	-890.31 kJ/mol	Exothermic reaction: Heat is released to the surroundings
ΔS°_rxn Entropy Change	-242.85 J/(mol·K) (-0.2429 kJ/(mol·K))	Entropy decreases: The system becomes more ordered
ΔG°_rxn Gibbs Free Energy Change	-817.90 kJ/mol	Spontaneous reaction: The reaction can proceed without external energy input

Thermodynamic Relationship:

ΔG° = ΔH° - TΔS°

ΔG° = -890.31 - (298.15)(-0.2429) = -817.90 kJ/mol

✓ Calculated value matches thermodynamic relationship

Step-by-step Calculation
Calculation Steps
Step 1: Apply thermodynamic formulas ΔH°_rxn = Σ ΔH°_f(products) - Σ ΔH°_f(reagents) ΔS°_rxn = Σ S°(products) - Σ S°(reagents) ΔG°_rxn = Σ ΔG°_f(products) - Σ ΔG°_f(reagents) Step 2: Calculate enthalpy change (ΔH°) ΔH°_rxn = Σ[coef × ΔH°_f(products)] - Σ[coef × ΔH°_f(reagents)] ΔH°_rxn = [ΔH°_f(CO₂(g)) + 2 × ΔH°_f(H₂O(l))] - [ΔH°_f(CH₄(g)) + 2 × ΔH°_f(O₂(g))] ΔH°_rxn = [(-393.522) + 2 × (-285.83) = -571.66] - [(-74.873) + 2 × (0) = 0.00] ΔH°_rxn = -890.31 kJ/mol Step 3: Calculate entropy change (ΔS°) ΔS°_rxn = Σ[coef × S°(products)] - Σ[coef × S°(reagents)] ΔS°_rxn = [S°(CO₂(g)) + 2 × S°(H₂O(l))] - [S°(CH₄(g)) + 2 × S°(O₂(g))] ΔS°_rxn = [(213.795) + 2 × (69.95) = 139.90] - [(186.251) + 2 × (205.147) = 410.29] ΔS°_rxn = -242.85 J/(mol·K) Step 4: Calculate Gibbs free energy change (ΔG°) ΔG°_rxn = Σ[coef × ΔG°_f(products)] - Σ[coef × ΔG°_f(reagents)] ΔG°_rxn = [ΔG°_f(CO₂(g)) + 2 × ΔG°_f(H₂O(l))] - [ΔG°_f(CH₄(g)) + 2 × ΔG°_f(O₂(g))] ΔG°_rxn = [(-394.389) + 2 × (-237.141) = -474.28] - [(-50.768) + 2 × (0) = 0.00] ΔG°_rxn = -817.90 kJ/mol Step 5: Verify using ΔG° = ΔH° - TΔS° ΔG°_calc = -890.31 - (298.15)(-0.2429) ΔG°_calc = -817.90 kJ/mol ✓ Values are consistent

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Reaction thermochemistry involves calculating the energy changes that occur during chemical reactions. The key properties calculated are:

Enthalpy change (ΔH°): The heat absorbed or released during a reaction at constant pressure
Entropy change (ΔS°): The change in disorder of the system during the reaction
Gibbs free energy change (ΔG°): Determines if a reaction is spontaneous or requires external energy

These calculations use standard formation data at 25°C (298.15 K) and 1 atm pressure.