Consider the electrochemical cell:
Volts
1.0 M KNO3
Ag Fe
1.0 M Ag NO3 1.0 M Fe (NO3)2
a) Towards which half-cell do the NO3
−
( ) aq in the salt bridge initially move? and why
The NO3- ions in the salt bridge will initially move towards the half-cell with the silver (Ag) electrode.
This is because in the half-reaction at the Ag electrode, Ag+ ions are reduced to metallic silver (Ag) according to the equation:
Ag+ + e- → Ag
As Ag+ ions are reduced to form Ag atoms, the overall charge within the Ag half-cell becomes more positive. To compensate for this, NO3- ions from the salt bridge will migrate towards the Ag half-cell to balance out the charge.