Key Terms
Eight steps
1. Write skeletal half-reactions (oxidation separate from reduction) 2.
Memory trick
AN OX = ANde is OXidation. RED CAT = REDuction at the CAThode.
Units
Volts (V) = joules per coulomb (J/C).
Cell potential formula
E(cell) = E(cathode) - E(anode)
Standard cell potential (E-degree cell)
Measured when all species are at standard state (1 M concentration, 1 bar pressure, 298 K).
Setup
Platinum electrode in 1 M H+(aq) with H2 gas bubbling at 1 bar, 298 K.
Half-reaction
2H+(aq) + 2e- --> H2(g) E-degree = 0.00 V
Full form
E(cell) = E-degree(cell) - (RT/nF) ln Q
Where Q is the reaction quotient
Products over reactants, each raised to their stoichiometric coefficients, using concentrations (or pressures for gases)
Concentration cells
A concentration cell has identical half-reactions in both half-cells; only the concentrations differ. E-degree(cell) = 0
Primary cells
Single use; cannot be recharged. Secondary cells: rechargeable; cell reaction is reversible.
Voltage
Approximately 1.2 V
Corrosion
Degradation of metals through natural electrochemical (redox) processes. Familiar examples: rust on iron, tarnish on sil
Combined
N(electrons) = (I x t) / F
Step-by-step calculation sequence
1. Calculate Q = I x t (convert t to seconds first) 2.