P&I 1 - Electrochemistry

Reduction

gain of electrons

Oxidation

loss of electrons

half-equation

an equation showing species and electron transfer in a redox reaction

Standard electrode potential

the measure of the inherent tendency of a chemical species to be reduced, compared against a standard hydrogen electrode.

ΔG= (electrochemistry)

-nFE

Salt bridge

A device used in electrochemical cells allowing ionic movement between the half-cells so the circuit is completed

Standard conditions (electrochemistry)

298K, 1atm, 1mol dm^-3

EMF (aka E_cell)

electromotive force

E_cell=

E_reduction - E_oxidation

Writing half-equation rules (acidic conditions)

• Check species are balanced

• Add water to one side to balance oxygens

• Add hydrogen ions to one side to balance hydrogens

• Check overall oxidation state of each side

• Add electrons to balance oxidation states.

Writing half-equations additional steps in alkaline conditions

• Add OH^- ions to the side with H+ to create water

• Add the same number of OH^- ions to the opposite side

• Cancel water molecules