Polarography Basic Analysis

These flashcards cover key concepts and definitions related to polarography as presented in the lecture notes.

What is the basic principle of polarography?

It involves the application of a linearly decreasing voltage and recording the resulting current.

What is a polarogram?

A plot of current versus the potential of the mercury electrode.

What does a step change in current indicate during polarographic analysis?

It indicates the electrolysis of the analyte.

What does the magnitude of the step change in polarography help determine?

The concentration of the analyte.

What is the purpose of calibrating a polarograph?

To ensure accurate quantitative analysis.

How is the concentration of an unknown determined in polarography?

By using a calibration graph plotted from standards with known concentrations.

What is the primary function of the mercury electrode in polarography?

To electrolyse the analyte at its surface.

What are the advantages of using a mercury electrode?

It is continuously exposed to fresh solution, inert to chemical reactions, easy to clean, and a good conductor.

What is the role of the auxiliary electrode in polarography?

It allows electricity to pass through the cell and facilitates electrochemical reactions.

What is the purpose of the reference electrode in polarography?

To measure and control the potential of the mercury electrode.

What occurs at the cathode during electrolysis?

Cations gain electrons and become neutral, forming solid metal in the case of metal ions.

What is the effect of overpotential on the rate of electrochemical conversion?

The current rises exponentially in relation to overpotential.

List the three ways ions can be transported to the electrode surface.

Convection, migration, and diffusion.

What does Fick's Law describe in the context of polarography?

The rate of diffusion depends on the concentration difference between the surface and bulk solution.

How is the magnitude of the diffusion limited current expressed mathematically?

iD = z A F D [M+]B / δ.

Why is it important to maintain a constant ionic strength during polarographic analysis?

To keep activity coefficients and equilibrium potentials constant.