HSC Chemistry First Hand Investigation 2009
Aim: To carry out a fist hand experiment in the extraction of red cabbage pigment, use this extracted pigment to standardize against know pH’s, test 5 household items to determine the possible pH of these items by using the standardization and assess the pigment’s ability to be used as a Universal Indicator.
Risk Assessment: When dealing with fire, the Bunsen burner should always be switched to the safety flame before lighting. There will also be hot water during the experiment, which means that safety goggles, bare skin kept to a minimal incase of a splash or spill of water. Leather shoes must also be worn when dealing with acids and hot water incase of any spills
Part 1: Extraction
Equipment: Shredded red cabbage, beakers, tripod, gauze mat, Bunsen burner and stirring rod.
1. Setup equipment as shown.
2. Put the shredded cabbage and pour in the beaker. Make sure that the amount of cabbage does not exceed the amount the beaker can store, and that the water level to be no more than ¾ full. 3. Light the beaker and stir until the solution boils and the colour of the water changes. 4. Pour the pigment onto another beaker and dispose of the remaining cabbage.
Part 2: Standardization
Equipment: Extracted pigment, test tubes, test tube rack, dropper, known pH’s (1,3,5,7,9,11,14), dropper
1. Setup the equipment as shown
2. Pour the known pH’s and household substances into test tubes and put the test tubes in a rack 3. Add droplets of the pigment with the dropper into the test tubes and observe and record any colour changes, the pigment should not be contaminated as it is to remain constant and the colour change the variable.
Part 3: Testing of Household Substances
Equipment: 5 Household substances, test tubes, test tube rack, extracted pigment, dropper
1. Pour the 5 substances into test tubes and put on a rack, repeat for the...
Bibliography: D. Irwin, R. Farrelly, D. Vitlin, P. Garnett – Chemistry Contexts 2 Second Ed., Pearson Education, 2006
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