My favourite practicals were always the Flame tests in Chemistry – they gave such amazing bright colours!
We had to dip a clean wire loop in a solution of any of the following metals: Barium, Lithium, Copper, Sodium, Potassium – most of these are in Group 1 of the periodic table (the first column on the left of the table)
Then we held the wire loop over a Bunsen burner, and the most amazing colour would spark up! I remember Barium was bright green, Lithium was a deep red colour, and Potassium was lilac!
My favourite practicals tend to involve liquid nitrogen! Nitrogen is normally a gas so you have to cool it A LOT to make it become a liquid, which means it’s really really cold. It’s quite dangerous if you use it wrong – it can cause severe cold burns if in direct contact with your skin – but it looks awesome when you pour it out and means you can do stuff like freeze food in seconds to the point that you can smash it with a hammer like its glass. (We did this for a primary school demonstation the other week and we had a lot of fun practising!)
But liquid nitrogen can also help you find out about the properties of materials. In my second year at uni we were able to look at how well certain materials maintain temperature by using liquid nitrogen. And nowadays some of our machines and experimental techniques rely on it.