IB Chemistry Web

CHEMISTRY EXTENDED ESSAY

These subject guidelines should be read in conjunction with the IB extended essay general guidelines.


Introduction

An extended essay in chemistry provides a candidate with an opportunity to investigate
personally a particular aspect of the materials of our environment. Such extended essays must be
characterized by a particular chemical emphasis within a more general set of scientific criteria.


Choice of Topic

It is important that the extended essay has a clear chemical emphasis and is not more closely related to another subject. Chemistry is the science that deals with the composition, characterization, and transformation of substances. A chemistry extended essay should therefore incorporate chemical principles and theory, and emphasize the essential nature of chemistry, relating to the study of matter and of the changes it undergoes. Although similar criteria apply to all extended essays in the experimental sciences, for an extended essay submitted in chemistry the topic chosen must allow an approach which distinctly involves chemistry. Where a topic might be approached from different viewpoints, the treatment of the material must be approached from a chemical perspective.

An extended essay in an interdisciplinary area such as biochemistry will, if registered as a chemistry extended essay, be judged on its chemical content, not its biological content. The scope of the topic and the research associated with it should enable all the criteria, particularly the subject specific criteria, to be addressed. A good topic is one where the single research question is sharply focused and is susceptible to effective treatment within the word limit. Perhaps the most important factor is the depth of treatment that can be given to the topic by the candidate.

Some topics may be unsuitable for investigation because of safety issues. For example, experiments involving toxic or dangerous chemicals, carcinogenic substances or radioactive materials should be avoided unless adequate safety apparatus and qualified supervision is available.

Other topics may be unsuitable because the outcome is already well known and documented in standard text books and the candidate may not be able to show any personal input. An example might be a study of the reactions of the alkali metals with water as this is already covered by the syllabus. However some care does need to be exercised in deciding whether a topic is suitable or not; for example, a few years ago the study of the allotropes of carbon may have been thought to be trivial but this would not be the case today.

The following examples of titles for chemistry extended essays are intended for guidance only. The pairings illustrate that focused topics (indicated by the first title) should be encouraged rather than broad topics (indicated by the second title).

  • "Spectrophotometric determination of trace amounts of lead in drinking water" is better than "Water analysis".
  • "The kinetics of oxidation of iodine ions with hydrogen peroxide in acidic solutions" is better than "Chemical kinetics".
  • "The analysis of the red dyes present in different brands of tomato ketchup by thin layer chromatography" is better than "The use of chromatography to separate materials".
  • "Is it better to use dried animal manure as a fertilizer or as a fuel?" is better than "Combustion and nitrogen analysis".
  • "The effects of sugar-free chewing gum on the pH in the mouth after a meal" is better than "Acid-base chemistry".

Other ideas for topics


Treatment of the Topic

An extended essay in chemistry may be based on literature, theoretical models or experimental data. Whichever category is chosen the candidate should ensure that sufficient data will be available for evaluation and that the topic can be researched accurately using locally available resources.

Candidates who choose to write an extended essay based on literature and/or surveys should ensure that their extended essay clearly shows its chemical basis. Essays written at the level of a newspaper or news magazine article are unlikely to achieve a high mark. Since chemistry is an experimental science, candidates are strongly encouraged to undertake experimental work as part of their research, although this is not compulsory. Any
experimental work which does form part of a chemistry extended essay should be described in sufficient detail to allow the work to be repeated by others, and candidates are strongly encouraged to research the literature first. Where possible, they should consult original research using scientific journals, personal communications and, where appropriate, the Internet. Textbooks should never be the only source of information. Data collected from an experiment designed by the candidate is of little value unless it is analysed, using appropriate scientific techniques, evaluated and perhaps compared with appropriate models.

It is possible to produce an extended essay in chemistry in which the candidate has used data collected elsewhere as the primary source. In such cases, the element of personal analysis and evaluation is important.

In any chemistry extended essay candidates should be able to demonstrate that they understand the theory underlying any experimental work and state any assumptions made. They should show an understanding of the results obtained and be able to interpret them with reference to the research question posed. They should be critical of inadequate experimental design, the limitations of the experimental method and any systematic errors. Candidates should be encouraged to consider unresolved questions in their research, and to suggest new
questions and areas for further investigation in their conclusion.


Assessment Criteria

J
Principles and ideas used to describe and explain the properties and behaviour of materials
Achievement level
 
0
There is no evidence of any principles or ideas relating to chemistry.
1
Some of the relevant principles or ideas relating to chemistry are mentioned but little use is made of them
2
Some of the relevant principles or ideas relating to chemistry are evident and used in a routine manner.
3
Many of the relevant principles and ideas relating to chemistry are evident and good use is made of them.
4
The relevant principles and ideas relating to chemistry are included and there is good evidence that they are fully understood and applied correctly.

 


 

K
Use of methods and sources appropriate to chemistry
Achievement level
 
0
The methods or sources used are not relevant or not appropriate to chemistry
1
The methods or sources used are appropriate to chemistry and relevant to the research question, but show minimal competence or are not carefully chosen.
2
The methods or sources used are appropriate to chemistry and relevant to the research question, and are carefully chosen, but used in a routine manner.
3
The methods or sources used are appropriate to chemistry and relevant to the research question, are carefully chosen, and used competently, and there is some evidence of a personal approach to their application.
4
The methods or sources used are appropriate to chemistry and relevant to the research question, are carefully chosen and used competently, and there is clear evidence of a personal approach to their application.

 


 

L
Reasoning surrounding the research and its limitations
Achievement level
 
0
There is no awareness of the quality of the experimental design or the quality of sources accessed. There are no explanations, confirmations or refutations
1
The quality of the experimental design or the quality of sources is briefly mentioned. There is no supporting evidence for explanations, confirmations or refutations.
2
The quality of the experimental design or the quality of sources is considered, but not analysed. There is little supporting evidence for explanations, confirmations or refutations.
3
The quality of the experimental design or the quality of sources is considered and subjected to limited analysis. There is some supporting evidence for explanations, confirmations or refutations.
4
Uncertainties in experimental data are thoroughly analysed and approximations in models are accounted for. Inadequate experimental design or any systematic error is exposed. The quality of sources accessed is verified by secondary sources or by direct calculations. Explanations, confirmations and refutations are supported by this analysis.