The standard electrode potentials at 298 K are given below:
`E_(Zn^(2+)| Zn )^(0)` = -0.76 volt and ,`E_(Fe^(2+)|Fe)^(0)` = -0.44 volt ,`E_(H^(2+)|H_(2))^(0)` = -0.0volt
Which of the two electrodes should be combined to form a cell having highest EMF? Identify the cathode and the anode and write the cell reaction. Also mention the direction of flow of electrons in the external as well as the internal circuit.

Explanation

To have maximum EMF the anode should have the minimum and cathode should have the maximum `E^(@)` therefore `Zn^(2+)//Zn` couple should be made as the anode while `1Cu^(2+)//Cu` should be made as the cathode the cell reaction `Zn(S)+Cu^(2+)(aq)rarrrZn^(2+)(aq)+Cu(s)`
EMF`=E_(cu^(2+)//Cu)^(@)0-E_(Zn^(2+)//Zn)^(2)=+0.34 -(-0.76)=+1.1 v`
the direaction of flow of electrons is from Zn to cu in the external circuit and from cu to zn in the internal circut the direction of flow of current is howver in the reverse direction i.e from cu to zn in the external circuit and from zn to cu in the internal circuit