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Questions and Answers
Which type of electrode is commonly used in polarography?
Which type of electrode is commonly used in polarography?
- Silver electrode
- Platinum electrode
- Graphite electrode
- Dropping mercury electrode (correct)
What is the role of the supporting electrolyte in polarography?
What is the role of the supporting electrolyte in polarography?
- To increase the sensitivity of the measurement
- To reduce the charging current
- To prevent interference from dissolved oxygen
- To stabilize the potential of the working electrode (correct)
What is the Ilkovic Equation used for in polarography?
What is the Ilkovic Equation used for in polarography?
- To calculate the concentration of the analyte
- To measure the polarographic current
- To calculate the standard potential
- To determine the diffusion coefficient (correct)
What is a disadvantage of the dropping mercury electrode (DME) in polarography?
What is a disadvantage of the dropping mercury electrode (DME) in polarography?
What are some applications of polarography?
What are some applications of polarography?
What are the different types of microelectrodes used in polarography?
What are the different types of microelectrodes used in polarography?
What is a polarogram?
What is a polarogram?
What is the Ilkovic Equation used for in polarography?
What is the Ilkovic Equation used for in polarography?
What are some factors that affect the polarographic wave?
What are some factors that affect the polarographic wave?
What are some applications of hydrodynamic voltametry?
What are some applications of hydrodynamic voltametry?
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Study Notes
Voltammetry and Polarographic Methods of Analysis
Polarography (Linear Scan Polarography)
- Polarography is a type of electroanalytical technique that measures the current-voltage relationship of an electrochemical reaction.
- Instrumentation includes:
- Microelectrodes:
- Dropping mercury electrode (DME)
- Static drop mercury electrode
- Rotating disc and ring disc electrode
- Cell for polarography
- Reference and counter electrode
- Circuit diagram
- Microelectrodes:
- Polarogram and polarographic currents:
- Charging or capacitive current
- Faradaic current
- Role of supporting electrolyte:
- Helps to maintain a constant ionic strength
- Reduces ohmic resistance
- Factors affecting polarographic wave:
- Concentration of the analyte
- pH of the solution
- Presence of interfering ions
- Ilkovic Equation:
- Relates the diffusion current to the concentration of the analyte
- Advantages and disadvantages of DME:
- Advantages: high sensitivity, reproducibility, and ability to analyze small samples
- Disadvantages: toxicity of mercury, difficulty in handling, and maintenance
- Polarographic maxima and maxima suppressors:
- Maxima: an increase in current due to the formation of a mercury film
- Suppressors: substances added to prevent the formation of maxima
- Interference due to dissolved oxygen:
- Oxygen can react with the analyte, causing interference in the measurement
- Applications:
- Qualitative analysis: identification of species present in the sample
- Quantitative analysis: determination of concentration using calibration curve and standard addition methods
- Specific examples of analysis:
- Analysis of Cu, Cd, Zn, and Pb from tap water and alloys
Hydrodynamic Voltametry
- Hydrodynamic voltametry: a type of voltammetry that uses a rotating disc or ring disc electrode to improve the mass transport of the analyte to the electrode surface
- Applications of hydrodynamic voltametry:
- Analysis of species in complex matrices
- Study of electrode kinetics and mechanisms
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