Q3(b). Ion-selective electrodes; pH with the glass electrode
What are ion-selective electrodes? How is glass electrode used in the determination of pH of a given solution?
Answer in brief
An ion-selective electrode is a membrane electrode whose potential depends on the activity of one particular ion; the glass electrode, with a calomel electrode, gives Ecell = K + 0.0592 pH at 25 °C, K being fixed with a buffer.
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Coversion-selective electrodeglass electrodepH measurementNikolsky–Eisenman equationasymmetry potentialfluoride electrode
All parts of Question 3
- 3(a) Surface energy when one drop is split into 125 drops10 marks
- 3(b) Ion-selective electrodes; pH with the glass electrode20 marks
- 3(c)(i) Enthalpy of vaporisation from the triple point to the critical point10 marks
- 3(c)(ii) Expansion of an ideal gas into a vacuum in an insulated box10 marks