Mixtures, Compounds and Separation - 12 December 2013

1. Separating mixtures. We made a mixture of sand, salt, iron filings and water, and then worked out how to separate the components. We used a magnet to take out the iron filings, filtration to remove the sand, and evaporation to remove the water. The mixture was reversible by physical processes.

2. Creation of a compound from two elements. Iron filings and sulphur were mixed to create a grey-and-orange powder. We could easily separate the iron filings from the mixture using a magnet. Next, the mixture was heated in a test tube until an orange glow was seen. The contents became a dark grey metallic-coloured liquid and then cooled to become a solid which would not come out of the test tube. We broke the test tubes open to examine the solid. It was a uniform compound called Ferrous Sulphide. As it is a compound, it can’t be separated into its constituent elements by physical means but only by chemical processes.

See Classic Chemistry Experiments : Iron and Sulfur reaction http://www.nuffieldfoundation.org/practical-chemistry/iron-and-sulfur-reaction and http://www.rsc.org/learn-chemistry/wiki/index.php?title=TeacherExpt:Iron_and_sulfur_reaction&oldid=4652 And Classic chemistry experiments: Separating Sand and Salt http://www.nuffieldfoundation.org/practical-chemistry/separating-sand-and-salt Royal Society of Chemistry collection of experiments on Separating and Purifying : http://www.nuffieldfoundation.org/practical-chemistry/separating-and-purifying RSC collection of practical activities on Mixtures and Pure Substances : http://www.nuffieldfoundation.org/practical-chemistry/mixtures-and-pure-substances