Reaction Energetics & Electrochemistry
Calculate ΔH of a reaction, activation energy, and electrode potentials calculation
Select what you want to calculate.
Activation Energy (Arrhenius equation)
Use the Arrhenius relationship to calculate activation energy or rate constants.
Result
Electrochemistry — Standard Cell Potential (E°cell)
Calculate the standard cell potential from standard electrode potentials (25 °C).
Cathode (reduction)
Anode (oxidation)
Result
Electrochemistry — Nernst Equation
Non-standard conditions (Q ≠ 1) at any temperature (T).
Result
Electrochemistry — ΔG and E Relationship
Relate Gibbs free energy change and cell potential.
Result
ΔH of a reaction (from standard enthalpies of formation)
Uses: ΔH°rxn = ΣνΔH°f(products) − ΣνΔH°f(reactants)
Reactants
Products
Result
Electrolysis — Faraday’s Laws
Relate current, time, charge, and amount of substance produced or consumed.
Result
Faraday’s Laws — Time or Current Required
Calculate the time or current needed to produce a given amount.
Competition at Electrodes (Aqueous, Inert Electrodes)
The species discharged is the one with the highest priority in the electrochemical order.
Water Electrolysis — Gas Volume Ratio
Overall: 2H₂O → 2H₂ + O₂, so H₂ : O₂ = 2 : 1 (moles and volumes at same T,P).
Half-reactions (reference)
Cathode: 2H₂O + 2e⁻ → H₂ + 2OH⁻
Anode (acidic/neutral): 2H₂O → O₂ + 4H⁺ + 4e⁻
Overall: 2H₂O → 2H₂ + O₂
Ratio: n(H₂):n(O₂) = V(H₂):V(O₂) = 2:1
Optional calculator (from charge)
Molecular / Empirical formula from mass percent
Enter element symbols and mass percentages. Add rows as needed. Molecular weight is optional.
Result
Fill in at least two elements and their percentages.
Radioactive Isotope Dating
Determine the age of a sample from radioactive decay using half-life.