On Monday, September 4, the Grade 11 chemistry class donned our lab coats and goggles and conducted an experiment about flame tests. Flame tests are done by scientists to figure out which metal makes up a certain compound.
The science behind flame tests is quite fascinating. You must have learnt in your science class that all matter is made up of tiny indivisible atoms. Atoms are essentially made up of a positively charged nucleus (which contains protons and neutrons) and electrons, negatively charged particles, which whizz around the nucleus. Below is a simplified diagram of a carbon atom.
Here’s the interesting bit: the electrons can absorb energy, resulting in them gaining that energy. This absorption is kind of like a sugar rush. The electron becomes really excited and jumps energy levels. However, it doesn’t hang around there for long. Eventually, it will return to its original position. When it does return, light is emitted. That light has distinct colours based on which element the atom is of.
Below is a diagram of a hydrogen atom which only has one electron. As can be seen, when the electron returned back to its original position, blue light is emitted (represented by the swirly arrow).
Flame tests are useful but can’t be used for detecting all metals. It has its limitations because not all metals can give flame colours. Anyway, here’s the basic procedure of the experiment:
- Dip an inoculation loop into the sample solution such as calcium chloride.
- Hold the loop over the bunsen burner flame. The colour of the flame will change for a few seconds.
- Clean the loop in acid and wash it with water. Then repeat!
Since this was our first chemistry lab of the year, we were a bit rusty and slow. However, that didn’t stop us from enjoying every second of it. Seeing the flame change colour right before our eyes was truly a sight to behold.
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