For a hald cell containing a Pt rod immersed in a solution of `1M HA, O _(2)(g)` is bubbled at 1 atm. The stnadard reduction potential for water formation is `1.23` V. Given a dissociation constant, `Ka=1 xx 10^(-4)` for HA, what is `E_("half cell") at 298 K` in V?

Options

A. `1.289`
B. `1.717`
C. `1.348`
D. `1.112`

Answer

D

Explanation

Given,
For a half cell containing pt rod, solution contains 1 M HA
`O _(2)` gas is bubbled at 1 atm standard reduction potential, `E _(0) = 1.23 V`
Dissociation constnat, `K _(A) = 1xx 10 ^(-4) ` for HA
Temperature, `T = 298 K`
The equation `E _("half-cell")` is given by,
`E _("half-cell")= E_(0) - (0.0592)/(N) log K _(A)`
`= 1.23 - ( 0.0592)/(2) log (1 xx 10 ^(-4)) (because` Number of electrons = 2)
` = 1.23 - (0.0592)/(2) x -4`
` therefore E = 1.348V`