Electrochemical Lab
Manual Equations

• Anson Equation
  • 
  • Q is charge (C)
  • n is number of electrons transferred
  • F is Faraday’s Constant (96,485.3 C/mol)
  • A is surface area of the working electrode (cm²)
  • C₀ is initial concentration of the analyte (mol/cm³)
  • D is diffusion coefficient of the analyte (cm²/s)
  • t is time (s)

   

• Corrosion Rate
  • 
  • CR is corrosion rate in milli-inches per year (mpy)
  • I_corr is corrosion current (A)
  • K is constant that defines the units for corrosion (1.288 x 10⁵ milli-inches/A·cm·year)
  • EW is equivalent weight (g/equivalent)
  • d is density (g/cm³)
  • A is area of the electrode (cm²)

   

• Cottrell Equation
  • 
  • i is current (A)
  • n is number of electrons transferred
  • F is Faraday’s Constant (96,485.3 C/mol)
  • A is surface area of the working electrode (cm²)
  • C₀ is initial concentration of the analyte (mol/cm³)
  • D is diffusion coefficient of the analyte (cm²/s)
  • t is time (s)

   

• Diffusion Layer Thickness
  • 
  • l is distance (cm)
  • D is diffusion coefficient of the analyte (cm²/s)
  • t is time (s)

   

• Faraday’s Law of Electrolysis
  • 
  • m is mass (g)
  • Q is charge (C)
  • M is molar mass (g/mol)
  • F is Faraday’s Constant (96,485.3 C/mol)
  • z is valance number

   

• Fick’s First Law of Diffusion
  • 
  • J is diffusional flux (mol/m²s)
  • D is diffusion coefficient of the analyte (m²/s)
  •  is concentration (mol/m³)
  • x is position (m)
  • 
  • i_d is diffusion limited current (A)
  • n is the number of electrons transferred
  • F is Faraday’s Constant (96,485.3 C/mol)
  • A is surface area of the working electrode (cm²)
  • D is diffusion coefficient of the analyte (cm²/s)
  • (dC/dx)₀ is concentration gradient at the surface of the electrode

   

• Formal Peak Potential
  • 
  • E^o is the formal potential of the analyte
  • E_pc is the cathodic peak potential
  • E_pa is the anodic peak potential

   

• Levich Equation
  • 
  • i_L is Levich current (A)
  • n is the number of electrons transferred
  • F is Faraday’s Constant (96,485.3 C/mol)
  • A is surface area of the working electrode (cm²)
  • D is diffusion coefficient of the analyte (cm²/s)
  •  is the angular rotation rate of the electrode (rad/s)
  • ν is the kinematic viscosity (cm²/s)
  • C is concentration of the analyte (mol/cm³)

   

• Nernst Equation
  •  
  •  
  • E is cell potential at the temperature of interest
  • E^o is the standard cell potential
  • R is the Molar Gas Constant (8.31446 J/mol•K)
  • T is temperature (K)
  • n is number of electrons transferred
  • F is Faraday’s Constant (96,485.3 C/mol)
  • Q is the reaction quotient

   

• Ohm’s Law
  • 
  • R is resistance
  • E is applied potential
  • I is applied current

   

• Peak-to-peak separation for reversible reaction
  • 
  • n is the number of electrons transferred
  • E_peak is the different between the cathodic and anodic peak potentials

   

• Randles – Sevcik equation
  • 
  •  
  • n is the number of electrons transferred
  • F is Faraday’s Constant (96,485.3 C/mol)
  • A is surface area of the working electrode (cm²)
  • D is diffusion coefficient of the analyte (cm²/s)
  • R is the Molar Gas Constant (8.31446 J/mol•K)
  • T is temperature (K)

   

• Ratio of peak heights for a reversible reaction
  • 
  • i_pc is cathodic peak current
  • i_pa is anodic peak current

   

• Steady-State Current at a Microelectrode
  •  
  • I is steady-state current (A)
  • n is the number of electrons transferred
  • F is Faraday’s Constant (96,485.3 C/mol)
  • D is diffusion coefficient of the analyte (cm²/s)
  • C^b is analyte concentration (mol/cm³)
  • r₀ is radius of the electrode (cm)

   

• Stern Geary Equation
  • 
  • I_corr is corrosion current (A),
  • R_p is polarization resistance
  • β_a is anodic Tafel constant
  • β_c is cathodic Tafel constant