87.10 Application of EMF and electrode potential 7.10.1 Computation of emf E 9+- For cell with single solution For cell with two electrolytic solutions: Zn(s)Znso(m,)CusO(m,) Cu(s) Cd(s)ICdso(a+)Hg SO4(s)IHg() RT e=O-=E+-In E 9-9 RT RT In RT m,y O4 o+Ina E=e+-In nF RT )-In a nF The mean activity coefficient(r+) has to be used in stead of the activity coefficient of individual ion(2 or r)7.10.1 Computation of emf For cell with single solution: Cd(s)|CdSO4 (a±) |Hg2SO4 (s)|Hg(l) 2 2 SO Cd 4 2 ln ln ( ) ln E RT RT a a nF nF RT a nF       − + + − + − + −  = −   = − − +     = − − E = −   + − For cell with two electrolytic solutions: Zn(s)|ZnSO4 (m1 ) ||CuSO4 (m1 ) |Cu(s) 2 2 Cu Zn ln RT a E E nF a   + + = − = + + − 1 ,1 2 ,2 ln RT m E E nF m     = + The mean activity coefficient ( ) has to be used in stead of the activity coefficient of individual ion (+ or - ). §7.10 Application of EMF and electrode potential