ULO3: Conduct reduction-oxidation reactions to demonstrate practical applications of electrochemistry.
The practical was the main area where I could demonstrate my ability to conduct the reactions. Whereas the research guided by the weekly prompts demonstrates my knowledge of the practical applications of electrochemsitry.
Besides the practical side of conducting the redox reactions. One of the ways I learned about the practical applications of electrochemistry was through reviewing journal articles.
Many of the prescribed readings simply explained the different types of electrochemistry and the potential applications. Although I could understand the intent of the applications, I struggled to understand the real world applications.
Looking at journal articles of real-world applications gave me an interest in electrochemistry and made me more likely to attempt to understand the concepts.
The end of topic questions asking to research a journal article that uses a particular type of analysis were extremely difficult. I could see that they used a particular technique and what the goal for the experiment and what the outcomes were. However, trying to understand how they went about it and the specifics were often too complex for me and I was only able to extract the main points.
I believe that if I was to look at this exercise again I would find it easier than I initially did. After having to look at protocols in order to build my own experiment in practical three, I believe I have gained a much stronger ability to deduce the relevant information from journal articles.
Literature use of Potential Step:
‘Kinetics of dissociative adsorption of formaldehyde on a Pt(111) electrode in sulphuric acid solutions studied using a programmed potential step technique and time-resolved Fourier transform IR spectroscopy’
- Studies the kinetics of dissociative adsorption of formaldehyde on platinum electrode using potential step techniques
- Goal to explain the electrocatalysis in solid-liquid interfaces at a molecular level.
- the kinetics of the adsorption was studied using potential step
- They used different potentials to observe the rate of adsorption. At low potentials, it was observed that the rate of adsorption quickly reached zero.
- Potential step was used due to its ability to create a program and record data at different potentials and times throughout the reaction
Although the question asked to find a journal article explaining Ion Selective Electrodes, I found that they were too complex for me and included a lot of chemicals and materials that I had not heard of before. Instead, I resorted to looking into basic information to understand at a basic level how to construct and ISE and the information it provides.
This was also done with the question about pseudo-reference electrodes. The basics about them were as much as I could understand at the time. However I believe since then, my knowledge has significantly grown and my ability to answer the questions would have improved due to the research I did for practical 3.
Ion Selective Electrode:
The cell contains a reference electrode as well as the ion selective electrode in the sample solution.
The inside solution of the ion selective electrode contains a solution of known concentration of the ion of interest
if the resulting potential is zero then the concentration of the sample and the known concentration solution is equal. If not then the electrode measures the potential difference across the membrane. The concentration can then be determined using the Nernst Equation.
The ISE can be subjected to interference from other electrodes. This can be accounted for using the Nikolskii-Eisenman equation which uses the selectivity coefficient to account for the interference
Describe the advantages and disadvantages of using just a silver wire or a platinum wire as a reference electrode. How are these electrodes called?
Pseudo reference electrodes need to be calibrated. They are not non polarizable electrodes and their potential can change depending on the experiment. They can also usually only be used in a strict range of conditions, such as pH and temperature.
Although the Piranha solution question was reasonably basic and mainly required knowledge about redox reactions. I struggled to be able to make any real observations about the mechanisms of the reaction and was only able to provide a statement of the properties of the components within the solution.
Why do you think the piranha solution is frequently used to eliminate all the organic contaminants in glassware?
Piranha solution is a mixture of sulfuric acid and hydrogen peroxide and is used to clean glassware due to its properties as a strong oxidiser. It also makes molecules with alcohol groups hydrophilic and therefore easily cleaned off.
H2O2: 1.8V
H2SO4: 0.7V
= easily reduced therefore acts as an oxidiser
Although I was unable to completely answer the weekly questions initially I believe given the opportunity again I would be more likely to be able to answer the questions in depth.
The theory of the practical applications was one which I struggled the most with. As seen in my practical reports marks, my ability to conduct the redox reactions in the practicals was of high quality. I did, however, struggle with answering the questions that asked me to demonstrate my understanding of the practical applications.
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