It is that time of year again when I get to see many Extended Essays in Chemistry. Two factors stand out. One is very pleasing to see – more and more students are actually writing genuine research  Essays rather than just writing up yet another practical experiment that simply follows the Internal Assessment criteria. This trend of following the IA criteria came in during the mid 2000s when the IA really took hold following the new programme for first examinations in 2003. It was responsible for students not achieving so well – not only in Chemistry, but also in Physics and Biology. During the past two years this trend has been reversed and the percentage of students gaining an A has started to go back up again. Perhaps of even more importance is that the percentage of students gaining A, B or C – i.e. writing an Extended Essay that is at least satisfactory with the opportunity to be awarded bonus points -  is also increasing. I am hopeful from what I have seen so far that this trend will continue this May session.

The second point is perhaps more to be expected – many students are not really able to express themselves well using the accepted chemical language. I have written on this at length with examples in the TOK section (as language is one of the four IB ‘ways of knowing’). I suppose it is not too surprising as apart from the IUPAC convention for naming organic compounds etc. the use of correct chemical terminology is not stressed on the programme. Also students are unlikely to be penalised heavily for the wrong use of terminology provided that they can be understood. I had put this down to teachers not having enough time to stress how to write ‘good chemistry’. However now I am not so sure. Look at the following diagram of the mass spectrum of sulfur and the sentences that follow:

You might expect that I have culled this from an Extended Essay written by a student. In fact it was written by an experienced IB teacher. I was recently asked to edit some material written by two IB teachers for publication. It surprised me to find that the teachers were making many basic errors in how they express their subject. If the teachers do not know how to write good chemistry how can we expect our students to do it? Sometimes it is actually wrong but at other times it just does not follow the accepted manner of expression. This may not matter except that the IB is quite particular about the conventions it uses (most, but not all, are taken from IUPAC). Using M instead of mol dm^-3 is not really wrong but it could confuse students as they will never see the use of M in an IB examination (except perhaps a specimen paper which has not gone through rigorous checking). In my page on the language of chemistry I make the point that perhaps when a student cannot answer a chemistry question it is not because they do not understand the chemistry but because they do not understand the language that the question is written in. The language page has many points listed but for starters next time you write a practical sheet, worksheet, some notes, a PowerPoint or a test it might just be worth checking the following.

• Elements and ions do not have capital letters (except when they start a sentence).

‘Silver nitrate solution reacts with sodium chloride solution to form a precipitate of silver chloride’ is correct. ‘Silver Nitrate solution reacts with Sodium Chloride solution to form a precipitate of Silver Chloride’ is wrong.

• Formulas should not be used on their own in sentences.

‘NaOH solution was titrated with HCl is wrong’. (HCl is a particularly bad formula to use as it could mean hydrochloric acid or hydrogen chloride). It is usually considered good practice to write the name of the chemical then, if the formula is needed, put it after the name. For example, aqueous silver ions, Ag⁺(aq), react with aqueous chloride ions, Cl^-(aq), to form a precipitate of silver chloride, AgCl(s).

• When using state symbols do not make them subscript.

     Ag⁺(aq) is better than Ag⁺_(aq).

• When a compound can exist in more than one oxidation state then include the oxidation state.

     Copper(I) bromide or copper(II) bromide.

• Physical constants are written in italics. This really seems to not be widely known.  If the constant is qualified then the qualification is written as a subscript but not in italics (unless it is the standard state sign in which case it is a superscript). For example, ∆H_c, pK_a, E.

• Use mol dm^-3 as the normal unit for concentration – not M.

• In a table where the units are given at the top (or on the axes of graphs) use the ‘slash’ notation for the units. For example, if you wish to express 10.0 s as a number then you need to divide by seconds 10.0 s/s = 10. At the top of the table it is therefore better to write time / s rather than time (s)^[1].

Hopefully you will now write better chemistry and your students will have less difficulty making sense of IB examination papers.