[Terry22]

Is it possible to identify an anonymous substance in a high school chemistry lab using the equipment available? For example, the students are given an unlabeled blue powder and asked to identify it. How would one go about this, and what would the likely answers be?

Is this too complex for a school lab? If so, is there a similar experiment one could ask students to do?

Terry

[cliverlong]

Slightly vague but ...

In the UK syllabus at GCSE, the little inorganic there is, discusses the analystical techniques

Solubility of salts / precipitates
Flames tests
Halogen displacements

I would suggest any reaction that results in a very visible results (especially colour change) and does not require accurate measurements of mass, volume or temperature might be suitable.

Maybe have a look at the EdExcel or CIE IGCSE papers for questions based on simple analtical tests along the lines of:

(the following is invented and probably doesn't correspond to any real compounds)

X, Y and Z are white powders

X dissolves in water
Y and Z do not dissolve in water
Y dissolves in aqueous ammonia
Z produces a blue precipitate on mixing with concentrated sodium hydroxide solution
X produces a brown gas on heating
Y and Z do not decompose on heating
Z produces a lilac flame on heating in a bunsen burner flame
etc. etc.


Now, in these risk averse times, I don't know whether you would be allowed to let the students attempt the experiments themselves ...

Clive

[Terry22]

Thanks for this, it sounds very useful.

I must confess the question is entirely hypothetical.  I have no intention of reproducing this experiment.  I'm writing a story in which the protagonist (a student) discovers a strange compound (powder or solid or whatever -- the colour isn't so important) and he/she must quickly identify it.  I'm ignorant when it comes to chemistry, so I was hoping that maybe there are common, simple experiments that students typically attempt at high-school that might make this scenario convincing.  I don't want to create a situation that's unbelievable, or wander into the realms of science fiction.  I was just wondering whether there are any (probably safe, possibly non-toxic) colourful powders or compounds that are easily identifiable by one or two very simple procedures?

I'll take a look at your recommended literature.

Thanks again.