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. 1.171
C. 1.348
D. 1.112

Answer

C

Explanation

Given, Standard reduction potential for water formation = 1.23V
Dissociation constant `(K_a)` for `HA = 1 xx 10^(-4)`
`E_(half - cell) ` at 298 K = ?
Number of electrons = 2
`E = E_0 - (0.0592)/(2) log Q (K_a)`
`E = 1.23 - (0.0592)/(2) log (1 xx 10^(-4) )`
` E = 123 - (0.0592)/(2) xx - 4`
`E = 1.348 V`