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Aug 31, 2023

Project: Upon successful completion of the module, students will be able to:
a. understand the methods of experimental design and the creation of new methods or novel modifications or combinations of existing methods.
b. be familiar with the current analytical literature and in particular to be able to review, select, read and critically discuss the papers most relevant to a particular topic;
c. handle and interpret of a range of analytical data;
d. demonstrate the techniques of communication including report writing, poster and oral presentation.

Topic - Determine the rate of Hydrolysis of Aspirin.

Colorimetric analysis of 2-hydroxybenzoic acid

Student worksheet

1. Pipette 10 cm3 of 2-hydroxybenzoic acid stock solution into a 100 cm3 volumetric flask. Make it up to volume with 0.025 mol dm-3 iron(III) nitrate solution. This is standard solution 1.

2. In a similar way make up standard solutions 2 to 5 using 8 cm3, 6 cm3, 4 cm3 and 2 cm3 of 2- hydroxybenzoic acid stock solution.

3. Measure the absorbance of each standard solution using the colorimeter, fitted with a suitable filter.

4. Plot a graph of absorbance against concentration of 2-hydroxybenzoic acid. This is the calibration graph.

5. Pipette 10 cm3 of solution of unknown 2-hydroxybenzoic acid concentration into a 100 cm3 volumetric flask. Make it up to volume with 0.025 mol dm-3 iron(III) nitrate solution. Measure its absorbance and calculate the concentration of 2-hydroxybenzoic acid.

The student must fulfil the following requirements:
• sufficient practical work must be carried out
• an acceptable dissertation of around 8000 words (± 800 words) must be submitted electronically via Turnitin.
• a poster for display in the University must be prepared
• an acceptable talk should be presented to the project panel and students

Rate of hydrolysis of aspirin
Student worksheet

1. Measure out 100 cm3 of the pH 7.5 buffer solution into a conical flask. Put this on a magnetic stirrer/electric hotplate and bring the temperature up to 70 °C.
2. Add 0.10 g of powdered aspirin to the buffer solution and stir the mixture gently until the aspirin is completely dissolved. No measurements should be made until all the solid has dissolved.
3. Pipette 5 cm3 of iron(III) nitrate reagent directly into a colorimeter tube. Pipette 1 cm3 from the reaction mixture and empty it into the colorimeter tube. Mix well and measure the absorbance. The intensity of the colour and, therefore, the absorbance value depends on the concentration of the hydrolysis product 2-hydroxybenzoic acid.
Note: The first reading represents "time 0" although it is likely that some decomposition will have already occurred.
4. Take 1 cm3 samples every 15 minutes for at least 2 hours and treat them as in step 4.
5. Use the calibration graph produced in Determination of 2-hydroxybenzoic acid to calculate the concentration of 2-hydroxybenzoic acid in solution at each time interval.

Processing results
The rate equation for the hydrolysis of aspirin is complex, but at a given pH in dilute aqueous solution the equation reduces to the first-order equation:

[A] is the concentration of aspirin
k is the rate constant (its value depends on temperature and pH).

1. From the concentration of aspirin, calculate the concentration of aspirin remaining in solution.

2. Plot a graph of aspirin concentration, [A], against time.

3. Measure the tangent at various point on the [A] vs time graph. These give the rate of reaction at various aspirin concentrations.

4. Plot a graph of rate of reaction against aspirin concentration. The slope of this graph gives the value of the rate constant, k, under the reaction conditions used.

5. The half-life of a reaction is the time it takes for the concentration of a reactant to halve or the concentration of a product to double. For a first order reaction the half-life is a constant value. No matter what the starting concentration of a reactant it takes the same time for this concentration to halve. From your results, work out the half-life for the hydrolysis of aspirin.

Project overview
The project is the single most important part of the MSc and is worth 60 credits - one third of the whole course. It is an opportunity for you to demonstrate your ability to plan and undertake a piece of research (analytical), interpret the results obtained and then present your findings in three different formats: a written report, a talk and a poster.

Project selection
The School uses a web-based system where academics upload details of the projects they are offering and the area to which they are most suited (forensic, biomedical, bioscience, pharmaceutical, etc.). Students then access the website and select their 5 preferred choices. The Module Tutor then reviews all the choices and allocates the projects. Generally, students will be allocated one of their choices but this cannot be guaranteed and the Module Tutor will select an unallocated project deemed most suitable depending on the student`s pathway.

Talk and poster
In September, there is a MSc Research Conference where you will be expected to give a talk and present a poster on your project. (To be confirmed as to whether this will be face-to-face or pre-recorded).
The poster should be A1 in size but can be either portrait or landscape. Posters prepared using Powerpoint can be printed prior to the date of the presentation. One copy only will be printed free of charge. You will be charged for subsequent printings if you make changes to your poster. (To be confirmed as to whether this will be face-to-face or on-line)
The talk will comprise a 9 - 10 minute presentation followed by a 2 - 3 minute question session (if face-to-face). Talks and posters are assessed by both academic staff and students.
Electronic copies of the talk and poster must be submitted via Brightspace by the due date.
All components of your project, report, notebook, talk and poster, will be scrutinised by an External Examiner (an independent academic from another institution) at the Course Assessment Board in October to confirm that the marking has been fair and consistent. Confirmed marks will be released shortly afterwards.

Attachment:- Colorimetric analysis.rar

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