Question

2. Calculate the standard emf of a cell that uses the Mg/Mg+2 and Cu/Cu+2 half-cell reactions at 25ºC. Write the equation for the cell reaction that occurs under standard-state conditions. (10 points)

Answer 1

2.71 V

Step-by-step explanation:

Usually in the cell notation, the left side shows oxidation. So,

Oxidation half reaction:

`Mg_((s))\rightarrow Mg^(2+)_((aq))+2e^-`
`E^o_(ox)=-E^o_(red)=-(-2.37\ V)=2.37\ V`

Reduction half reaction:

`Cu^(2+)_((aq))+2e^-\rightarrow Cu_((s))`
`E^o_(red)=0.34\ V`

Overall reaction:

`Mg_((s))+Cu^(2+)_((aq))\rightarrow Mg^(2+)_((aq))+Cu_((s))`

`E^o_(cell)=E^o_(ox)+E^o_(red)= (2.37+0.34)\ V=2.71\ V`