Galvanic cells

how is standard cell potential (E cell) measured

measured at a specified temperature with no current flowing and all components in their standard states

standard electrode potential (E°half-cell)

potential of a given half-reaction when all components are in their standard states. {At SATP and 1mol/L concentration for aqueous solutions}

notation for a voltaic cell

Anode | Anode Solution || Cathode Solution | Cathode

inactive electrode

to provide a surface for electrons to move without the metal itself getting involved in the chemistry

active electrode

active component in half-cell; a reactant/product in overall reaction

anode

(an, ox) NEGATIVE (-) electrode in voltaic (galvanic) cell. Polarized current enters circuit

cathode

(red cat) POSITIVE (+) electrode in galvanic cell. Current leaves a polarized electrical device

salt bridge

contains non-reacting cations & anions, often K+ & NO3- that don’t interfere w reaction

purpose of salt bridge

maintain electrical neutrality; keep charges in electrolytes constant → allowing the redox reaction to continue

why is a salt bridge needed

e- must keep moving for electricity to flow. Without salt bridge, electrolyte gets more positively/negatively charged, thus slows oxid/reduc cuz charged ions start repelling each other. Salt bridge helps ion freely between between half-cells

why does salt bridge deplete

the ions within them migrate into the half-cells to neutralize accumulating charges, eventually diffusing out. But the salt bridge is made not just of salt, but of an absorbent material such as filter paper. This will soak up the electrolytes it is dipped into, so ions from the solutions will diffuse into it