“Not in the least, chemistry is never boring”.
“Sir is being daft again”.
Of course some students think that if they now have carte blanche to burn all their possessions, such as plastic pens, to see what happens, ie, they can mess about. That is why they like it.
The Bunsen burner has a powerful hold in UK practical chemistry. Its presence in practical work ultimately defines the set out of the school laboratory.
The cheapest option is to place the gas pipes (and other services) around the outside of the room, with just tables and chairs in the middle. The raison d’être for this is that labs should be adaptable to all types of teaching approaches with tables moving around, to accommodate group work and argumentation. How often I wonder does room alteration happen? With services around the perimeter and in terms of practical work, students now have their backs to the teacher when using the dangerous Bunsen, it is not possible to place 30 students around the perimeter and there are obstructions such as cupboards and notice boards with bits of paper on them.
I have even see labs with no demonstration bench and have been told that this is to discourage demonstration because it is too teacher-centric. (No it is cheaper not to have services under the floor to the teacher’s bench!)
There are many ways of using a Bunsen but most have two controls; the yellow “safe” flame and the full-on blast. Control of supplying heat by using air collar and gas tap is not common. Even less common is that you can hold a Bunsen by the base and heat a liquid gently from the side. This is really important in distillation.
So is electrical heating an alternative to the Bunsen?
The electrical heating mantle and hotplates cost over £100 each, they are expensive and they take a long time to warm up a liquid (there is a fixed time to a lesson!) and they are difficult to use when heating test tubes.
They are used extensively in University chemistry departments and here we have a problem. Conditions in University chemistry departments are very different from school labs (even more so than 50 years ago), so new teachers coming teach in a school usually resort to how they were taught; use a Bunsen; yellow flame and full blast! (This problem is something I might write about later)
The temperature of the flame is about 900ᵒC, enough to completely soften soda glass (and the heat shock causes catastrophic breakages) and distort borosilicate glass. At that temperature, sulfates are decomposed to sulfur dioxide and trioxide and even sodium nitrate to brown nitrogen dioxide; an observation not in the text book (is this supposed to happen?) I am always uncomfortable directly distilling a flammable organic solvent from a pear-shaped Quickfit flask, but it has to be done sometimes (cyclohexanol to cyclohexene). Thus I try in school chemistry practicals, to suggest procedures that use boiling water baths, which let’s face it are also dangerous.
I have been informed that many children (and some teachers) are very scared of lighting a flame such that neither will use them at GCSE level. Sometimes, it is the teacher only who lights the Bunsen for the student. There have been minor burns reported to CLEAPSS and parents and employers have questioned why we use such dangerous equipment. However, knowing how to deal safely with fire is good education!
So when I suggest that I can do most of my chemistry with a spirit burner and an electric kettle, the traditionalists are horrified.
Any heating equipment is not without safety issues. Many spirit burners (see equipment page for my version) are old aromatherapy bottles, that had loose tops and held up to 100 ml of ethanol, so any spill resulted in a nasty fire fire. Some American States ban their use although I suspect there have been more serious injuries from American Football and other sports than the chemistry laboratory so why not ban … err better not go there. The worst incident we had in the UK was a students who bent over a candle and his shirt caught fire which then melted a rubber emblem on his vest into his chest. This went to court. Subscribers to of CLEAPSS can read about it in Bulletin 122 (2005). It was deemed an unfortunate accident with no direct fault of the teacher. The school pleaded guilty to not training its staff in fire safety. The fire officer wanted much more restrictions on the use of candles but that started to get very silly. Whether there were civil actions afterwards, I do not know but no doubt the insurance people settled out of court if there were. Hot water can scald and of ourse you never really know a hot plate is on (unless there are specail signs)
I have to a Bunsen for glass work, heating calcium carbonate and other carbonates, carbon/metal oxide reactions keeping a boiling-water bath boiling. However for activities like dissolving salts, Disilling liquids with boiling points below 90C (see picture at top) , Fehling’s and Tollens racions solution, and warming up solutions for rate determinations, a kettle of boiling hot water can be used.
For dehydration of hydrated metals salts, microscale cracking and reduction of metal oxides with hydrogen in a Pasteur pipette or glass tube, the spirit burner can be used.
Robert Bunsen, well his University Instrument Maker, Peter Desaga, see http://www.rsc.org/chemistryworld/Issues/2007/October/ClassicKitBunsenBurner.asp, designed the burner for a specific purpose. In a similar way you should ask yourself “is a Bunsen burner really required for this experiment? Its use is a part of risk assessment under the UK COSHH Regulations.
Are we using the Bunsens today?
“Boring lesson then”.
“No I have done a risk assessment I find that hot water from a kettle is quicker and safer to react copper oxide with dilute sulfuric acid.”
“Do you usually talk like this?”
PS on Bunsen burner quality and misuse
Danger: The quality of some inexpensive imported Bunsen burners is very worrying. Students turn the air-hole collar to get the hot flame and flame extinguishes itself; the air-collar hole is too large. The jet is sometimes too large leading to a flame thrower and a poor hot flame. In the UK we use natural gas. Bunsen burners using LPG have an even smaller diameter air-holes and leaking LPG is very serious hazard as the gas is heavier than air. If you connect a natural gas Bunsen to LPG and you have a flame thrower. For you in the UK, by British, as you buy long-lasting quality if they are regularly serviced.
Misuse: under the direction of some teachers, students directly place solids in the flame (on a wooden splint); the solids fall down the chimney, blocking the jet, and seizing up the collar.