The following electrochemical cell has been set up: `Pt(1)|Fe^(3+),Fe(a=1)||Ce^(4+), Ce^(3+)(a=1)|Pt(2)`. If an ammeter is connected between two platinum electrodes, predict the direction of the flow of current. Will the current increase or decreases with time ? Given: `E_((Fe^(3+)|Fe^(2+)))^(@)=0.77V and E_((Ce^(4+)|Ce^(3+)))^(@)=1.61V`

Explanation

For electrochemical cell,
`Pt(1)|Fe^(3+),Fe(a=1)||Ce^(4+),Ce^(3+)(a=1)|Pt(2)`
`E_(Fe^(3+)|Fe^(2+))^(0)=0.77V" "E_(Ce^(4+)|Ce^(3+))^(@)=1.61V`
`therefore" "E_("cell")^(@)=E_("cathode")^(0)-E_("anode")^(@)=1.61-0.77=0.84V`
Since `E_("cell")^(@)` is `+ve,` the cell reaction will occur spontaneously. Hence, the flow of current will be from cathode ot anode (right to left), and the current will decrease with time.