Question

The standard emf for the cell using the overall cell reaction below is +2.20 V: 2Al(s) + 3I2 (s) → 2Al3+ (aq) + 6I− (aq) The emf generated by the cell when [Al3+] = 5.0 ⋅ 10−3 M and [I−] = 0.10 M is ________ V. The standard emf for the cell using the overall cell reaction below is +2.20 V: (s) + (s) (aq) + (aq) The emf generated by the cell when [] = 5.0 M and [] = 0.10 M is ________ V. 2.20 2.41 2.10 2.30 2.23

Answer 1

Answer: +2.10V

Explanation:

$2Al(s)+3I_2(s)\rightarrow 2Al^{3+}(aq)+6I^-(aq)$

Using Nernst equation :

$E_{cell}=E^o_{cell}-\frac{0.059}{n}\log K$

$E_{cell}=E^o_{cell}-\frac{0.059}{n}\log [Al^{3+}]^2\times [I^-]^6$

where,

$E^o_{cell}$ = standard emf for the cell = +2.20 V

n = number of electrons in oxidation-reduction reaction = 6

$E_{cell}$ = emf of the cell = ?

$[Al^{3+}]$  = concentration = $5.0\times 10^{-3}M$

$[I}^{-}]$  = concentration = $0.10M$

Now put all the given values in the above equation, we get:

$E_{cell}=+2.20-\frac{0.059}{6}\log [5.0\times 10^{-3}]^2\times [0.10]^6$

$E_{cell}=2.10V$

The standard emf for the cell using the overall cell reaction below is +2.10 V