Electroanalysis - Ion Selective Electrodes

Flashcards based on essential concepts and details from the lecture on Electroanalysis and Ion Selective Electrodes.

What is the function of a reference electrode in electroanalysis?

It allows the electrical circuit to be completed and exhibits a highly stable potential difference.

What is the main purpose of an ion-selective electrode?

To detect specific ions in a solution.

What types of membranes are used in ion-selective electrodes?

Glass membranes, sparingly soluble inorganic salt membranes, liquid membranes, and polymer-immobilised ionophore membranes.

How is a glass membrane for ion-selective electrodes created?

It is made by fusing aluminium oxide, sodium oxide, and silica.

What is the significance of conditioning a glass membrane?

Soaking it in 0.1 M HCl creates a hydrated layer necessary for functionality.

What is one common error with glass membranes at high pH levels?

The 'alkaline error' occurs around pH 12 and above.

What property must sparingly soluble inorganic salt membranes possess?

They must be ionic conductors at room temperature.

What is LaF3 used for in electroanalysis?

It is used as a fluoride selective electrode.

What is the Nernst equation used for?

To calculate the electrical potential difference based on ion concentrations.

How are liquid junctions formed in electroanalysis?

Through a salt bridge or porous plug.

What is an important consideration when reducing liquid junction potentials?

Using electrolytes with similar transport numbers for cations and anions.

Describe the reversible reaction involved in a silver/silver chloride electrode.

Ag+Cl− (s) + e− (metal) ↔ Ag(s) + Cl− (aq).

What is a key advantage of the silver/silver chloride electrode?

It is simple to use and inexpensive.

What role do ion-selective electrodes play in electrochemical measurements?

They require a stable potential difference to maintain an electrochemical equilibrium.

How does the performance of an ion-selective electrode depend on sample concentration?

The overall potential difference is sensitive to the concentration of the sample.

What is necessary for the Ag/AgCl coating in electrochemical applications?

The coating needs to be porous to allow equilibrium.

What are some examples of suitable electrolytes for minimizing liquid junction potential?

Potassium chloride, potassium nitrate, and ammonium nitrate.