electrode potentials Flashcards
what is the E nought value?
how easily the half cell loses electrons (is oxidised)
describe how electrode potential equations are written
in reduced form
reduction is always the forward direction
electrons on the LEFT
how are E nought values used to decide whether something is oxidised or reduced?
most negative = oxidation
most positive = reduction
use the following equations & values to decide what is oxidised/reduced
Zn2+ + 2e- –> Zn (-0.76)
Cu2+ + 2e- –> Cu (+0.34)
Zn is most negative so is oxidised = reducing agent
use the following equations to create an overall equation
Zn2+ + 2e- –> Zn (-0.76)
Cu2+ + 2e- –> Cu (+0.34)
Zn is oxidised so must be flipped so it is in reduced form
Zn –> Zn2+ + 2e-
Zn + Cu2+ <–> Zn2+ + Cu
what standard reference are E nought values measured against?
standard hydrogen electrode (SHE)
what is the value of the SHE?
0
what are the standard conditions for SHE?
gas pressure → 100kPa
temperature → 298 K/25°C
concentration → 1 mol dm⁻³
where is the 1 mole of H+ ions obtained from for creating a SHE?
1mole HCl or 1/2mole H2SO4
state the calculation for standard cell potential (overall E nought value)
Enought reduced - Enought oxidised
(pos - neg)
what is cell notation?
simplified setup of a cell using vertical lines
where is the negative half cell positioned in cell notation?
left of double line
what do single lines represent in cell notation?
physical state changes
state the general cell notation
reduced | Zn2+ || Cu2+ | Cu
how are 2 aq ions separated in cell notation
comma
