Lesson 13: Experiments Monday 16 August 2010

That day, Mdm Riza had carried out a distillation experiment before we stepped into the laboratory. Her aim was to collect pure water, which has a boiling point of 100 degree celsius. From the experiment, I learnt that distillation is to separate just two subsatnces in a mixture. When the temperature reaches 100 degrre celsius and water is collected, the water is PURE. However, if the temperature is 99.5 degree celsius, then the water collected isn't PURE.
We conducted an experiment on paper chromatography. Through this experiment, I understood how paper chromatography works. A spot of dye which is placed above the pencil mark on a strip of filter paper is inserted into a test tube of alcohol, which is known as the solvent. The spot of dye must be above the alcohol level so that the colours do not dissolve in the alcohol. The filter paper will absorb the alcohol and as the alcohol slowly spreads upwards, the dye gets separated. The colour with the most solubility will rise to the top while the colour with the least solubility will remain at the bottom.
I've learnt that paper chromatography and distillation can only be used for a mixture of liquids. For distillation, porcelain chips are used to ensure smooth boiling of the water in the distillation (conical) flask.