On May 10th, I went to the Salters’ Festival of Chemistry competition. In our team was me (Rhea Sandhu 8W), Rosalind Morgan 8V, Alice Owen 8T and Jade Westfoot 8T. During the day we did two practical activities. These were very enjoyable and interesting! Then we had a practical lecture in a lecture theatre.
There were five suspects and a victim, all with traces of white powder and ink on them. In our group of four, we were to split into two pairs to each separately do an experiment for each, testing the powder with hydrochloric acid, sodium hydroxide and distilled water, and checking the pH with Universal Indicator and for the ink, finding its properties using chromatography.
In the meantime, if a pair had finished before another, we were told to work out a code to find each suspects’ alibi, and use the information as well as the cross-referenced results from each test to determine a final suspect. The test results would determine whether the properties of a particular powder or ink was more similar to or the same as the substances found on the victim’s body. We won third prize for our work in this challenge.
The aim of this challenge was to create the colours of the rainbow by combining universal indicator with either hydrochloric acid (an acidic solution), distilled water (a neutral liquid), sodium hydroxide (an alkaline solution) or a further combination of them. We only needed to create half a dozen colours, so we thought it easy. Creating colours red, green and purple were easy, an acidic solution turns red in indicator, a neutral turns green and an alkaline turns purple. These we had already, but to determine the exact amounts of the right liquid to add to which solution was a process mostly of trial and error, although common knowledge did come into it. We recorded our methods and managed to procure a set of rainbow colours!
After this was lunch, and then the demonstration lecture began… This was a very exciting part of the day, despite the fact that ‘lecture’ does sound less than appealing! The lecture was on how to create a firework. We learnt that there are several primary components to making a firework, for example something to cause light, something to cause a bang, and something to act as fuel or a catalyst.
For fuel, one would generally use charcoal or coal, but in the lecture we explored different ideas for fuel, including hydrogen. However, this can be dangerous. We were shown an example of an uncontrolled hydrogen situation, such as leaving a lit splint near a balloon of hydrogen. We were ordered to cover our ears, and the resulting bang was very loud! The bottle went ricocheting around the room!
One would need substances to produce components needed for the fire triangle (oxygen, fuel and heat) so a substance that produces oxygen is needed.
Colour can be produced by using different metals in the chemical mixture, for example, strontium makes red, copper blue, barium green, sodium yellow / orange, and iron burns a gold colour.
As for a bang, an easy way to create one is allowing dry ice (sublimed carbon dioxide) or liquid nitrogen to evaporate quickly in a small space. As something evaporates or melts, it expands, so if the reaction takes place quickly the container will suddenly burst open at a point due to heightened pressure in the container, propel the container slightly into the air and cause rather loud bangs, akin to the ones heard in fireworks, though not safe to hear at a close distance. We were shown examples of this and many other experiments during the session, such as methods of how to get oxygen out of a reaction using a catalyst, and seeing up close dry ice and liquid nitrogen.
I do hope you have learned more about chemistry and enjoyed an account of the exciting and fun events of the Salters’ Festival of Chemistry!
By Rhea Sandhu, Year 8