The standard reduction potentials of two half cells `Al^(3+) (aq) | Al`and `Mg^(2+)(aq) | Mg` are -1.66V and -2.36V respectively. Calculate the standard cell potential. Write the cell reactions also.

Answer

0.70 V,3 Mg+2 `AI^(3+)rarr3Mg^(2+)+2` AL

Explanation

Since `Mg^(2+)(aq)//"Mgelectorde" =-2.36V` is at a lower potential than `AI^(3+)(aq)/(AI) "electrode" = 1.66V therefore Mg^(2+)(aq)//Mq` electrode acts as the anode and `AI^(3+)(aq)//AI` acts as the cathode in other words Mg loses electrons and `AI^(3+)` in accepts electrons thus the cell reaction is
`3Mg+2AI^(3+)rarr3Mg^(2+)+2AI "and" E_("cell")^(@)=E_(AI)^(@),AI-E_(Mg)^(2+),Mg^(@)=-1.66-(-2.36)=+0.70V`