Question

Calculate the e.m.f. of the cell,
`Mg(s)//Mg^(+)(0.1 M)||Ag^(+)(1xx10^(-4) M)//Ag(s)`
`E_(Ag^(+)//Ag)^(@)=+0.8" V ", E_(Mg^(2+)//Mg)^(@)=-2.37" V "`
What will be the effect on e.m.f. if concentration of `Ag^(+)` is increased to `1xx10^(-3) M` ?

Answer 1

Correct Answer - 2.96`" V "` ;increases
Step I. Calculate of emf of the cell
Cell reaction : `Mg(s) +2Ag^(+)(1.0xx10^(-4) M) to Mg^(2+)(0.1" M ")+2Ag(s)`
`E_(cell)=E_(cell)^(@)-(0.0591)/(n)"log"([Mg^(2+)])/([Ag^(+)]^(2))=[0.8-(-2.37)]-(0.0591)/(2)"log"(0.1)/((1xx10^(-4))^(2)`
`=3.17-(0.0591)/(2)" log "10^(7)=3.17-0.02955xx7`
`=3.17-0.20685=2.96315V=2.96" V "`.
Step II. Effect of increasingconcetration of `Ag^(+)` ions on EMF of cell
The EMF of the cell with increase on inbcreasing the concentration of `Ag^(+)` ions in solution.