Question

Which of the following reactions would have the smallest value of K at 298 K? Which of the following reactions would have the smallest value of K at 298 K? A + B → 2 C; E°cell = -0.030 V A + 2 B → C; E°cell = +0.98 V A + B → C; E°cell = +1.22 V A + B → 3 C; E°cell = +0.15 V More information is needed to determine.

Answer 1

Answer:

The reaction with smallest value of K is :

A + B → 2 C; E°cell = -0.030 V

Explanation:

$nFE^o_{cell}=RT\ln K$

where :

n = number of electrons transferred

F = Faraday's constant = 96500 C

$E^o_{cell}$ = standard electrode potential of the cell

R = Gas constant = 8.314 J/K.mol

T = temperature of the reaction = $25^oC=[273+25]=298K$

$K$ = equilibrium constant of the reaction

As we cans see, that standard electrode potential of the cell is directly linked to the equilibrium constant of the reaction.

• Higher $E^o_{cell}$ higher will be the value of K.
• Lower $E^o_{cell}$ lower will be the value of K.

So, the reaction with smallest value of electrode potential will have smallest value of equilibrium constant. And that reaction is:

A + B → 2 C; $E^o_{cell} =-0.030 V$