3: Sabbatical - Wednesday - Chemistry

Today, I feel so honoured. The HSC vice-chairman Nicholas Chuan is teaching me. As you can see from the title, it is another day on chem. However, today was more interesting. It is somewhat a continuation from yesterday. We dealt more with pH, but still did some experiments on chemical reactions. My favourite experiments? Dissapearing ink, rainbow reactions, diffusion in liquids, cool inflation. 4/7 of the experiments. Since there are 4, let's give the other 3 a miss.

Dissapearing ink was made from 0.5ml of ethanol with phenolphthalein mixed with 4.5ml of water, with 1 drop of sodium hydroxide. We smeared it on some fabric, and put ammonia on it. The ammonia was in a fume box. It was quite cool. In the end, after ammonia was applied, the words appeared!

Rainbow reactions was a colourful experiment. 10ml of sodium hydroxide + 15 drops of universal indicator was mixed with 15ml of hydrochloric acid. This mixture was transfered to a burette. 5ml of sodium bicarbonate was added in the burette, and covered fast with para-film. Then, we inverted the burette and saw a rainbow! Fascinating!

Diffusion in liquids was done with three things.

1: lead(ll) nitrate and potassium iodide.

2: copper(ll) sulfate and sodium hydroxide.

3: iron(ll) sulfate and sodium hydroxide.

The first one produce yellow crystals, the second blue crystals while the fourth was a dark green line. The blur crystals were by far the nicest. The yellow ones spoil easily. One shake and the whole solution turns murky with yellow stuff.

Cool inflation was COOL. 2 spatula each of sodium hydrogen carbonate and citric acid was mixed with 25ml of natural indicator. The whole plastic bag inflated and when we touched the solution, it was very cold. Another group added just 10ml of natural indicator and their bag was on the brink of explosion.