Summary EDEXCEL A-LEVEL CHEMISTRY NOTES: REDOX 2

,
, 14 -
Redox
2

ectrode potentials
E

· dipping a metal into a solution ofits own ions is called

a
cell
half / electrode

o when a metal is dipped into a solution of its own metal ions

an equilibrium is set up

equilibrium lies to the left, the metal aquires a
o the
if

negative charse due to a build up ofelectrons on the

metal (negative potential
·
if equilibrium lies to the right, a positive charge builds up


as electrons have been used up to form metal (positive poventrial
· Cannotbe measured directly

o to measure, it needs to be connected to another half
cell

and the potential difference is measured


·
Combining the two makes an
electrochemical cell


· the standard hydrogen electrode is assisted potential O
of

· known as the primary standard


E
lectrochemical cell

· two cells joined together to give a complete circuit

o metals joined by a wire


·
solutions joined with a saltbridge


dapiece ofpaper soaked in unreactive ions) (e.s. KNO3


Standard Hydrogen Electrode

2H (aw) (2(g)
+



2e E0 +0.00V
-
+


=




Standard conditions
· cell concentration -
1.0 moldin-3 of all ions in halfequation
· cell temperature -
298K
·
Cell Pressure -
lOokPa only affects cell
gasses half

·
Standard Potential -

Go


Cell Notation


BO ↑ o ↓- Salt bride
lefthand cell right hand cell
-Phase boundre
- ROOR hishest oxidation
=




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