The purpose of this lab is to identify two different unknown organic compounds, through investigating different chemical properties by various experiments. The chemicals could be alkanes (hexane), alkenes (hex-1-ene) or alcohols (methylpentan-1-ol or hexa

Review of essay

Rating: 3 star(s)

Response to the question

The candidate has written up an experiment they carried out to identify unknown substances. They included all the required sections - an introduction, method, results, conclusion, and evaluation. However, they have written the method and results sections out twice - proof checking should have spotted this, and their method lacks detail and a labelled diagram. However, they have used their results to identify the substances correctly and so come to a well-supported conclusion, and as part of this did an additional test on one substance to double check their results, showing a thorough, scientific approach.

Level of analysis

The candidate has carried out several tests, and used their results to analyse the substances. However, they do not appear to have thoroughly understood the tests - for example claiming that the fact that one substance did not boil at 75 degrees meant that it must be an alcohol - to support this they should have given the boiling points for all the substances and thus decided that the only ones above 75 degrees were alcohols, or described how they have eliminated the other possibilities (by earlier tests). This section of the report could have been written more clearly to clarify this.
One test they have clearly understood and analysed well is the bromine test for unsaturation - they have given a very good explanation of the reaction. They have also shown knowledge of advanced chemistry by describing the differences in boiling point between branched and unbranched molecules.

Quality of writing

The candidate's spelling, punctuation, and grammar is very good throughout. However, their explanations and descriptions could have been clearer as they tended to use long sentences where a short bullet point or table could have been used, and often repeated themselves. Although headings have been used throughout, some information was still in the wrong sections, for example explanations of the chemistry behind the reactions were spread all over the report and often repeated, and all the information about reducing errors was included in the evaluation rather than in a 'reducing errors' section in the method. They have also not stuck to convention to give a fully detailed method - instead they simply order you to 'test the solubility' with no indication as to how to do this. A scientific report should allow the reader to precisely copy the author's method, and so needs more detail.
they have ended the report well by suggesting one way to further develop on their analysis, having mentioned possible causes of errors.
Overall, their quality of writing is acceptable, but the report needs proof reading and more detail.