Question
Cell reaction is spontaneous when
A.
$$E_{red}^ \circ $$ is negative
B.
$$E_{red}^ \circ $$ is positive
C.
$$\Delta {G^ \circ }$$ is negative
D.
$$\Delta {G^ \circ }$$ is positive
Answer :
$$\Delta {G^ \circ }$$ is negative
Solution :
When the value of $$\Delta {G^ \circ }$$ is negative, the cell reaction is spontaneous.
$$\Delta {G^ \circ } = - nF{E^ \circ }$$
where, $$n =$$ number of electrons take part
$$F = $$ Faraday constant
$${E^ \circ } = $$ $$EMF$$ of the cell
Thus, for a spontaneous reaction, the $$EMF$$ of the cell must be positive.