One aim of the microscale approach was to make available, by using modern materials and techniques, demonstrations in chemistry teaching that were traditionally difficult to set up, perform and show meaningful results. Yet they are essential for students to see (live; not video) if they are to understand the difficult concepts of chemistry and one such area is "ions". The electrolysis of molten lead bromide is one demonstration that provides direct evidence that salts consist of charged particles (ions) and not molecules.
I had a helpline recently from a school technician who suggested my microscale method, which he had set up in a previous school, to his new teachers. But no! Teachers said this microscale method is not dramatic enough (had they ever tried it?), even though it provides better chemical evidence to improve students’ knowledge. Is a chemical demonstration for knowledge/teaching/learning or drama? The equipment for both is shown in the visual presentation.
I had a helpline recently from a school technician who suggested my microscale method, which he had set up in a previous school, to his new teachers. But no! Teachers said this microscale method is not dramatic enough (had they ever tried it?), even though it provides better chemical evidence to improve students’ knowledge. Is a chemical demonstration for knowledge/teaching/learning or drama? The equipment for both is shown in the visual presentation.
The beauty to me of the microscale approach carried out in a BOROSILICATE glass tube is that
There is a perception amongst some teachers that microchemistry is not real chemistry because it was not how they were taught. They are also concerned that students would be at a disadvantage in exams, although there is no evidence of this. The ideas are there to complement the traditional demos and experiments and add variety to teaching with an alternative approach.
I am old enough to remember similar comments when Nuffield Chemistry was introduced in the late 1960s and 70s.
Still, a demonstration can be enjoyable if not a drama!
- you see LED light up.
- you can remove the iron nail from the melt and on cooling make a few marks of lead on paper - a lead pencil
- you see the red bromine vapour and can test it with starch iodide paper.
- it can be set up quickly, and does not require a fume cupboard,
- it uses minimal amounts of lead bromide (0.5 to 0.7 g), which is toxic, and large amounts need careful waste management, and
- it can be projected using webcams, onto a screen.
There is a perception amongst some teachers that microchemistry is not real chemistry because it was not how they were taught. They are also concerned that students would be at a disadvantage in exams, although there is no evidence of this. The ideas are there to complement the traditional demos and experiments and add variety to teaching with an alternative approach.
I am old enough to remember similar comments when Nuffield Chemistry was introduced in the late 1960s and 70s.
Still, a demonstration can be enjoyable if not a drama!
Textbooks will tell lead bromide is an insoluble salt. However enough lead bromide dissolves to allow an electric current to pass though and if that is the case electrolysis will happen. This is unusual as both the molten and the dissolved salts give the same products at the electrodes. It is more common that water, the solvent, undergoes electrolysis on at least one electrode. Then again some teachers will worry that I am using toxic lead salts. Activities should be banned on risk, not on hazard. Equipment, as PPE and rules are put in place as when contact sorts are played. I am using 0.5 g of lead bromide here. I believe he education benefit overrides the very small risks
