The standard cell potential for : 3A(s) + B+3(aq) → 3A+(aq) + B(s) is E° = 2.00 V. How does Ecell compare to Eo when [A+] = 0.50, [B3+] = 1.5 x 10-3 at 298 K.

E cell = 1.962 V

Given

E° cell = 2.00 V

Required

E cell at 298 K

Solution

The potential cell for nonstandard conditions we can use the Nernst equation  

For temperature T = 298 K,  

Reaction

3A(s) + B+3(aq) → 3A+(aq) + B(s)

Half Reaction

3A(s)⇒3A⁺(aq)+3e⁻

B⁺³(aq)+3e⁻⇒B(s)

n = 3 (3 electron transfer)

Q = the reaction quotient  :

E cell :

in the given question, the partial pressure is calculated by using the ideal gas equation, that is, pv = nrt

here, p is pressure, v is volume = 25 l, n is number of moles = 0.0104 moles, r is gas constant = -0.0821 l.atm / mol.k

t is temperature = 273 k

p = nrt / v

p = (0.0104 mol × 0.0821 l.atm / mol.k × 273 k) / 25 l

= 0.0093 atm