Level0AdvancingChemistryassessment1brief xPractical5_Data1 xExperiment5-DeterminevitamineCcontentusingaredoxtitrationmethod StructuredScientificReportfoundation1 x
 

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Hi i have included the assignment brief and a structure template we have to go by

Assessment brief: Advancing Chemistry

MBSMD0ADC

Assessment 1:

Scientific Paper

Title	Date Due at 2pm	Proportion of module mark	Word limit	Return date
Scientific Paper	24/04/2018	50 %	2000 words	15/05/2018

Rationale

Presenting and effectively communicating scientific experiments and data is an important skill. The standard written format is to present scientific work as a scientific paper. This assessment will help you to understand the different sections within a scientific paper and what information should be included within them. It will also help you to develop your skills in writing in a clear and concise way, how to present data as figures and to begin to discuss your data within the wider context of similar experiments from the literature.

Task

Choose one of these practicals

· Determination of iron in a vitamin tablet using spectrophotometry

· Determination of Vitamin C concentration using a redox titration method

· Enthalpy of reactions and Hess’s law

· Reaction Kinetics – Determining the rate equation for a chemical reaction

Write your chosen practical in the form of a scientific paper. Word limit: maximum 2000 words (excluding references and appendix). The scientific paper needs to include an abstract, introduction, materials and methods section, results section and discussion section. Further information as to what you should include in each section will be discussed in class and on Blackboard.

Submission details

Submission of all work is by 2pm on Tuesday 24th April 2018

You must include the marking grid following as part of your submission. Your work cannot be graded without the marking grid and failure to include it registers as a non-submission of work.

All submissions are via turnitin unless specified here: N/A

Level 0 Generic Marking Grid Bioscience Suite

MARKING GRID Foundation

(0-100%)

Coherence and organisation of assignment. Clarity of expression (incl. spelling, grammar, punctuation). Communication and presentation (appropriate to discipline)

Content and knowledge: evidence of reading, quality of sources used

Critical thinking. Analysis. Conclusions

80-100

Strong logical organisation and coherence enhances fulfilment of the assignment objectives.
Fluent writing style appropriate to the assignment. Grammar and spelling accurate.
Effective communication which demonstrates a strong understanding of the discipline.

Demonstrates broad and/or in-depth independent reading from appropriate sources.
Sources used are acknowledged in the text and reference list and used effectively to support discussion.
Referencing follows a systematic approach, appropriate to the discipline.
Uses a balanced combination higher quality secondary sources and some primary sources.

Emerging critical thinking is consistently integrated into the work. Shows some ability to evaluate theories / concepts / assumptions / data.
Makes very good use of a range of relevant analytic techniques. Shows good ability to compare alternative theories / analytic approaches (where relevant).
Conclusions are well developed and analytical. They are grounded in theory / evidence / literature. They form an integrated part of the overall argument / discussion.

70-79

Demonstrates logical organisation and coherence.
Language fluent. Grammar and spelling mainly accurate.
Good communication in a format appropriate to the discipline.

Evidence of independent reading from a fairly wide range of appropriate sources.
Sources used are acknowledged in the text and reference list and used to support discussion.
Referencing follows a systematic approach, appropriate to the discipline.
Uses a balanced combination of higher quality secondary sources.

Demonstrates appropriate critical thinking grounded in theory / evidence / literature.
Makes good use of established techniques of analysis relevant to the discipline. Shows some developing ability to compare alternative theories / analytic approaches (where relevant).
Conclusions show some critical insight. They relate clearly to evidence / theory / literature.

60-69

Demonstrates sound, thoughtful organisation.
Language generally fluent. Grammar and spelling mainly accurate.
Communication is effective and in a format appropriate to the discipline.

Evidence of independent reading from a range of appropriate sources.
Sources used are acknowledged in the text and reference list.
Referencing follows a systematic approach, appropriate to the discipline.
Mostly uses higher quality secondary sources.

Demonstrates some critical insight, with clear links to evidence / theory / literature.
Makes effective use of established techniques of analysis relevant to the discipline. Shows some awareness of alternative theories / analytic approaches (where relevant).
Logical conclusions are drawn, which are derived from evidence / theory / literature.

50-59

Demonstrates generally sound, conventional organisation.
Meaning clear, but language not always fluent. Grammar and/or spelling contain errors.
Communication is generally effective and shows awareness of the discipline’s academic style.

Evidence of some independent reading from appropriate sources.
Attempts to follow systematic approach to the citation of sources, appropriate to the discipline.
Uses appropriate secondary sources.

Demonstrates some conventional critical insight and recognises alternative positions.
Makes fair and/or conventional use of established techniques of analysis, relevant to the discipline.
Generally sound conclusions are drawn which are supported by evidence / theory / literature.

40-49

Shows limited organisation.
Generally understandable, but language contains errors which detract from the argument.
Generally clear but limited evidence of discipline’s academic style.

Evidence of reading from appropriate sources. Literature is presented in a descriptive way.
Some attempt to cite sources in the text but contains inaccuracies, inconsistencies and/or omissions.
Integration between text and reference list is inconsistent.
Some use of appropriate secondary sources, but also draws upon some unreliable and/or inappropriate sources.

Demonstrates limited critical insight. Some recognition of alternative positions.
Makes satisfactory but limited use of established techniques of analysis, relevant to the discipline.
Some relevant conclusions are drawn which are derived from limited understanding of evidence / theory / literature

20-39

Poorly presented and structured but partially understandable.
Meaning often unclear and/or frequent errors in grammar and/or spelling.
Communication is unstructured and unfocused and/or in a format inappropriate to the discipline.

Very limited evidence of reading and/or inappropriate sources used and/or engagement with the literature very superficial.
Citations of sources in the text are inconsistent, inaccurate and/or incomplete.
Makes some use of appropriate sources, but also strongly draws upon unreliable and/or inappropriate sources.

Critical thought and/or analysis very limited and/or incoherent.
Attempts at analysis ineffective and/or uninformed by the discipline.
Limited or ineffective attempt to draw together arguments.

0-19

Disorganised and/or incoherent.
Meaning unclear. Poor spelling, grammar and punctuation.
Communication is disorganised and/or incoherent and/or shows no understanding of the discipline.

Little or no evidence of engagement with relevant literature.
Little or no acknowledgement of sources of information in text and/or reference list.
Uses unreliable and / or inappropriate sources.

No evidence of critical thought.
Lacks any analysis.
Lack of conclusions, or unsubstantiated and/or invalid conclusions drawn.

Table 2: Orange juice titration

Initial Burette Reading

Final Burette Reading

Volume of 0.005 M iodine solution added (mL)

39.5 ml

24.5 ml

24.5 ml

12 ml

12 ml

0 ml

Average volume used

Table 3 Apple juice titration

Initial Burette Reading

Final Burette Reading

Volume of 0.005 M iodine solution added (mL)

0 ml

Average volume used

9.7 ml	6.5 ml
6.5 ml	2.6 ml
2.6 ml

Table 4: Kiwi fruit

Initial Burette Reading

Final Burette Reading

Volume of 0.005 M iodine solution added (mL)

0 ml

Average volume used

20.4 ml	15.2 ml
15.2 ml	6.8 ml
6.8 ml

Table 5: Strawberry

Initial Burette Reading

Final Burette Reading

Volume of 0.005 M iodine solution added (mL)

Average volume used

53.5 ml	39.9 ml
39.9 ml	26.5 ml

Table 5: Peas

Initial Burette Reading

Final Burette Reading

Volume of 0.005 M iodine solution added (mL)

Average volume used

38.8 ml	29.6 ml
29.6 ml	19.8 ml

1

5 – Determination of Vitamin C Concentration using a redox
titration method

Introduction

Vitamin C, (ascorbic acid), is an essential antioxidant needed by the human body. You will

determine the vitamin C concentration in a solution by a redox titration using iodine. As the iodine

is added during the titration, the ascorbic acid is oxidised to dehydroascorbic acid, while the

iodine is reduced to iodide ions. Reaction 1 shows the overall reaction whereas reaction 2 and

3

represent the two half-reactions.

Ascorbic acid + I2 → 2 I
−

+ Dehydroascorbic acid (1)

I2 + 2e- → 2 I

–

The iodine formed is immediately reduced to iodide as long as there is any ascorbic acid present.

Once all the ascorbic acid has been oxidised, the excess iodine is free to react with the starch

indicator, forming the blue-black starch-iodine complex. This is the endpoint of the titration.

You will use this method to determine the vitamin C content in various sources of vitamin C, such

as vitamin C tablets, fresh fruit juice, packaged fruit juice and solid fruits and vegetables.

Materials (per student pair)

Equipment Chemicals

Volumetric flask (100 or 200 mL)

20 mL pipette

50-mL burette, stand and clamp;

Cheese cloth

Mortar and pestle

Food processor

Conical flask (250 mL)

Iodine Solution

Starch Indicator solution

Vitamin C tablets (1 per pair)

Orange juice

Apple juice

Fresh fruit/vegetables

DI water

Health and Safety:

Iodine stains badly – gloves should be worn in addition to lab coat and safety

glasses.

(3)

(2)

2

Sample Preparation

For vitamin C tablets:

Dissolve a single tablet in 200 mL of distilled water (in a volumetric flask if possible).

For fresh fruit juice:

Strain the juice through cheesecloth to remove seeds and pulp which may block pipettes. Make

the extracted solution up to 100 mL with distilled water (if needed).

For packaged fruit juice:

This may also need to be strained through cheesecloth if it contains a lot of pulp or seeds. Make

the extracted solution up to 100 mL with distilled water (if needed).

For fruits and vegetables:

Cut a 100 g sample into small pieces and grind in a mortar and pestle. Add 10 mL portions of

distilled water several times while grinding the sample, each time decanting off the liquid extract

into a 100 mL volumetric flask. Finally, strain the ground fruit/vegetable pulp through cheesecloth,

rinsing the pulp with a few 10 mL portions of water and collecting all filtrate and washings in the

volumetric flask. Make the extracted solution up to 100 mL with distilled water.

Alternatively the 100 g sample of fruit or vegetable may be blended in a food processor together

with about 50 mL of distilled water. After blending, strain the pulp through cheesecloth, washing

it with a few 10mL portions of distilled water, and make the extracted solution up to 100 mL in

a volumetric flask.

Solutions

Iodine solution: (0.005 M). Weigh 2 g of potassium iodide into a 100 mL beaker. Weigh 1.3 g of

iodine and add it into the same beaker. Add a few mL of distilled water and swirl for a few

minutes until iodine is dissolved. Transfer iodine solution to a 1 L volumetric flask, making sure to

rinse all traces of solution into the volumetric flask using distilled water. Make the solution up to

the 1 L mark with distilled water.

Starch indicator solution: (0.5 % (w/v)). Weigh 0.25 g of soluble starch and add it to 50 mL of

near boiling water in a 100 mL conical flask. Stir to dissolve and cool before using.

Method: Titration

1. Pipette 20 mL of the sample solution into a 250 mL conical flask and add about 150 mL of

distilled water and 1 mL of starch indicator solution.

2. Rinse and fill the burette with the 0.005 M iodine solution. Record the initial volume in the

table below.

3. Titrate the sample with the iodine solution. The endpoint of the titration is identified as the

first permanent trace of a dark blue-black colour due to the starch-iodine complex. Record the

final volume in the burette in the table below

4. Calculate the volume of 0.005M iodine solution added during the titration.

5. Repeat the titration with further aliquots of sample solution until you obtain 3 titres that agree

within 0.1-0.2 mL of each other.

3

Table 1: vitamin C tablet titration

Initial Burette Reading Final Burette Reading Volume of 0.005 M iodine

solution added (mL)

Average volume used

Table 2: Orange juice titration

Initial Burette Reading Final Burette Reading Volume of 0.005 M iodine
solution added (mL)

Average volume used

Table 3 Apple juice titration

Initial Burette Reading Final Burette Reading Volume of 0.005 M iodine
solution added (mL)

Average volume used

Table 4: Solid fruit/vegetables titration

Initial Burette Reading Final Burette Reading Volume of 0.005 M iodine
solution added (mL)

Average volume used

4

Calculations

For each of the different juices, perform the following calculations:

Vitamin C tablets

1. Calculate the average volume of iodine solution used from your titres.

Average volume = mL

2. Calculate the number of moles of iodine in this average volume using the molarity of the iodine

solution in the burette.

3. Using the equation of the titration (below) determine the number of moles of ascorbic acid

reacting. Show your calculations below:

Ascorbic acid + I2 → 2 I
−

+ Dehydroascorbic acid

Moles of ascorbic acid reacting =

4. What is the number of moles of ascorbic acid in the original vitamin C tablet?

5. Calculate the amount of ascorbic acid, in mg, in the vitamin C tablet.

5

Apple Juice

1. Calculate the average volume of iodine solution used from your titres.

Average volume = mL

2. Calculate the number of moles of iodine in this average volume using the molarity of the iodine
solution in the burette.

3. Using the equation of the titration (below) determine the number of moles of ascorbic acid
reacting. Show your calculations below:
Ascorbic acid + I2 → 2 I
−
+ Dehydroascorbic acid

Moles of ascorbic acid reacting =

4. Calculate the molar concentration of ascorbic acid in the original apple juice solution.

5. Calculate the concentration, in mg/100mL of ascorbic acid, in the original apple juice

solution.

6

Orange Juice

1. Calculate the average volume of iodine solution used from your titres.

Average volume = mL

2. Calculate the number of moles of iodine in this average volume using the molarity of the iodine
solution in the burette.

3. Using the equation of the titration (below) determine the number of moles of ascorbic acid

reacting. Show your calculations in the box below

Ascorbic acid + I2 → 2 I
−
+ Dehydroascorbic acid

Moles of ascorbic acid reacting =

4. Calculate the molar concentration of ascorbic acid in the original orange juice solution.

5. Calculate the concentration, in mg/100mL of ascorbic acid, in the original orange juice

sample.

7

Solid fruit/vegetables:

1. Calculate the average volume of iodine solution used from your titres.

Average volume = mL

2. Calculate the number of moles of iodine in this average volume using the molarity of the iodine
solution in the burette.

3. Using the equation of the titration (below) determine the number of moles of ascorbic acid
reacting. Show your calculations below:
Ascorbic acid + I2 → 2 I
−
+ Dehydroascorbic acid

Moles of ascorbic acid reacting =

4. Calculate the molar concentration of ascorbic acid in the original fruit/vegetables solution.

5. Calculate the concentration, in mg/100mL of ascorbic acid, in the original fruit/vegetables

solution.

Structured Scientific Report

Student Number:______________________

Title of your study: please think of a suitable descriptive title for your project. “Chemistry Practical” is not a sufficient title!

Abstract (150 words maximum):

Please write a 150 word max summary of your entire project which introduces what you have done, summarises the main findings of your experiment and suggests why this is important.

Introduction (maximum 600 words): Please write a concise,
referenced
introduction that outlines the work undertaken in your study, the wider field it sits in, what your aim is and how experimentally you are going to do this. Set the scene. Not everyone who reads your paper will be an expert in your field, so you must include enough information so that the rest of your paper is understandable.

Introduction continued (if needed)……

Materials and Methods (maximum 250 words): What materials you used, what experiments you performed and how you did them. You must include enough detail so that someone can repeat your experiments based on your paper alone. This is written concisely in the past tense / third person. No “I” or “We” did this please. Nor is this a recipe or a list of instructions. DO NOT copy the methods from the practical manual, these are NOT in the correct format.

Results (500 words maximum): Here you present the results of you investigations but do not discuss them. The Results section is usually written as prose, in paragraphs
and is not just made up from figures and tables.
Make sure that any figures and tables are numbered and include appropriate figure legends
below figures and table legends
above
tables. Use as many pages as necessary.

Discussion/conclusion (500 words maximum): Explain the results of your experiments and refer to relevant references from the literature. Do the results that you found agree with what you can find in the literature? If not, then why do you think not? You must suggest further work and can suggest improvements to the study. Your discussion will end with a concluding paragraph summarising your overall discussion – DO NOT PUT ANY NEW INFORMATION INTO THIS PARAGRAPH. Remember, the conclusion is just a single paragraph, not an entire page!

References (not included in word count): Only include references that you use within your report and list them according to the Harvard style of referencing. You can find out how to correctly use the Harvard Referencing style by following this link: https://learn.canterbury.ac.uk/webapps/portal/execute/tabs/tabAction?tab_tab_group_id=_35_1

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