The quinhydrone electrode `(Q,H^(o+)|H^(2)Q)` is used in conjunction with a saturated calomel electrode, as represented below`:`

`EMF_(cell)=0.264V` at `30^(@)C`. Calculate the `pH` of unknown solution at this temperature.
Given `:E_(calomel)=0.24V` and `E^(c-)._(2H^(o+),Q|H_(2)Q)=0.7V`

Explanation

`(` Note that the value `2.303(RT)/(F)`at`30^(@)C=0.06)`
`E_(S C E )=0.242V`
`E_(qui nhydron e)=E^(c-)._(qui n hydron e )-0.06pH(`at`30^(@)C)`
`:. E_(cell)=E_(RHS)-E_(LHS)=E_(qui n hydron e)-E_(SCE)`
`0.264V=0.7-0.06pH-0.24(` at` 30^(@)C)`
`:. pH=(0.7-0.24-0.264)/(0.06)=3.266~~3.27`