Saturday, August 29, 2009

Lab Week

Sorry I haven't been on top of posting, but we have been performing some exciting labs to examine physical and chemical changes. Students did an excellent job following directions and practicing safe lab procedures.

This first video is one of the most exciting examples of a chemical change and it actually had two different chemical changes. video The elemental copper (Cu) reacts with Nitric acid releasing nitrous oxide (the brown gas - more commonly an ingredient in smog). A brown liquid was left in the erlenmeyer flask. Water was added and another chemical reaction occurred resulting in a blue liquid.

Another fun chemical change involved the combustion of Magnesium. This chemical change produced a blinding white light. All that remained after combustion was ash. Sometimes magnesium is used in fireworks.

Students were able to see a precipitate form when mixing lead nitrate and potassium iodide. A precipitate is a solid that forms when two liquids are mixed and a double replacement reaction occurs. Two clear liquids were mixed and formed a bright yellow precipitate with a clear liquid (it looked yellowish because of all the precipitate.

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