We were very lucky indeed to have another visit by Mr Tim Harrison from the School of Chemistry, University of Bristol. Last Friday morning, Year 7 and Year 9 students, accompanied by the teachers who would normally be teaching them, were treated to a lecture and practical demonstrations by this expert chemist.
Everyone was enthralled by the demonstrations. The topic was about the gases of our atmosphere, how they compare to those on other planets in our solar system, and how our atmosphere has changed over time. Loud bangs guaranteed our attention, colour changes fascinated and liquid nitrogen, boiling at -196⁰Celsius was a real attention grabber. If anyone is silly enough to put their fingers into liquid nitrogen they will freeze “like fish fingers” and then drop off within 5 seconds! Hopefully the students now understand what is meant by a cryogenic liquid.
Helium has a trivial use in filling party balloons because it is a relatively safe gas and has the lowest density apart from hydrogen. We were reminded that helium has a much more important use in medicine: MRI and CT scanners use helium as a coolant for the superconducting magnets. The world market for helium has seen its price double in each of the last two years, should we really be “wasting it” for party balloons?
Mr Harrison has many roles within his job; he helps to educate some of our best chemistry students at university, he trains teachers too, and he visits schools to give practical demonstrations. For Year 9 students particularly he dropped many examination hints; test a Year 9 student to see if they can explain “exothermic” reactions, “physical and chemical changes”, and the expansion of gases when there is a temperature increase.
Mr Harrison’s work with schools is sponsored by the Royal Society of Chemistry, we are very grateful that he was able to visit us with such an effectively illustrated and enjoyable lecture.