This chapter discusses the principles of electrochemistry, covering the generation of electricity through chemical reactions and the application of electricity in chemical processes.
Electrochemistry – Formula & Equation Sheet
Essential formulas and equations from Chemistry - I, tailored for Class 12 in Chemistry.
This one-pager compiles key formulas and equations from the Electrochemistry chapter of Chemistry - I. Ideal for exam prep, quick reference, and solving time-bound numerical problems accurately.
Key concepts & formulas
Essential formulas, key terms, and important concepts for quick reference and revision.
Formulas
E_cell = E_cathode - E_anode
E_cell represents the cell potential (in volts), E_cathode is the standard electrode potential of the cathode, and E_anode is the standard electrode potential of the anode. This formula calculates the electromotive force of a galvanic cell.
ΔG° = -nFE°_cell
ΔG° is the change in standard Gibbs free energy (in joules), n is the number of moles of electrons transferred, F is Faraday's constant (≈ 96485 C/mol), and E°_cell is the standard cell potential (in volts). This relation links thermodynamics and electrochemistry.
E = E° - (RT/nF) ln(Q)
E is the cell potential at non-standard conditions, E° is the standard cell potential, R is the gas constant (8.314 J/K·mol), T is the temperature (in Kelvin), n is the number of electrons transferred, and Q is the reaction quotient. This equation describes how cell potential changes with concentrations.
κ = 1/R
κ represents conductivity (in S/m) and R is the resistance (in ohms). This equation relates the conductivity of an electrolytic solution to its resistance.
Λ_m = κ/c
Λ_m is molar conductivity (in S m²/mol), κ is conductivity (in S/m), and c is concentration (in mol/m³). This formula is used to describe the conductivity of an electrolyte per mole.
ΔG° = -RT ln(K)
ΔG° is the standard Gibbs free energy change, R is the universal gas constant, T is the temperature (in Kelvin), and K is the equilibrium constant. This equation connects thermodynamics to chemical equilibria.
R = ρ(l/A)
R is resistance (in ohms), ρ is resistivity (in ohm meters), l is the length of the conductor (in meters), and A is the cross-sectional area (in m²). This formula describes how the physical dimensions of a conductor affect its resistance.
Q = It
Q is the total electric charge (in coulombs), I is the current (in amperes), and t is time (in seconds). This formula calculates the total charge passed through an electrolytic cell.
Faraday's First Law of Electrolysis: m = (Q/F) * (M/z)
m is the mass of substance produced at an electrode (in grams), Q is the total charge (in coulombs), F is Faraday’s constant, M is the molar mass of the substance, and z is the number of electrons per ion. This law relates the amount of substance produced to the quantity of electricity used.
n = (m/M)
n is the number of moles of substance, m is the mass (in grams), and M is the molar mass (in g/mol). This formula converts mass to moles, useful in stoichiometric calculations.
Equations
Zn(s) + Cu²⁺(aq) → Zn²⁺(aq) + Cu(s)
This is the overall redox reaction in a Daniell cell, where zinc is oxidized and copper is reduced, producing electrical energy.
Cu²⁺(aq) + 2e⁻ → Cu(s)
This is the reduction half-reaction at the cathode of a galvanic cell where copper ions gain electrons to form copper metal.
Zn(s) → Zn²⁺(aq) + 2e⁻
This is the oxidation half-reaction at the anode of a galvanic cell where solid zinc loses electrons to form zinc ions.
2H₂O(l) → O₂(g) + 4H⁺ + 4e⁻
This is the oxidation reaction that occurs at the anode during the electrolysis of water.
2H₂(g) + O₂(g) → 2H₂O(l)
This is the overall reaction in hydrogen fuel cells, converting hydrogen and oxygen into water while producing energy.
E_cell = E_cathode - E_anode
The cell potential is derived by subtracting the anode potential from the cathode potential, assessing the energy available from a galvanic cell.
nF = Q
n represents the number of moles of electrons, F is Faraday's constant, and Q is the total charge in coulombs. This equation relates charge to the number of moles of electrons transferred.
K = [Products]^[coefficients] / [Reactants]^[coefficients]
This is the expression for the equilibrium constant K, describing the ratio of concentrations of products to reactants at equilibrium.
m = (Q/ZF)
This relation indicates the mass deposited at an electrode in an electrochemical reaction, where Q is total charge, Z is valence, and F is Faraday's constant.
V = IR
Ohm's Law states that voltage (V) equals current (I) times resistance (R), fundamental in evaluating circuits in electrochemical cells.
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