HSC SCIENCE EXTENSION
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The Effect of Metamorphism on
the Chemical Reactivity of Calcium Carbonate Minerals
By Luke Byrnes
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The aim of this project was to see if metamorphism affects the chemical reactivity of calcium carbonate minerals. On average, marble took far longer to dissolve in the same conditions than limestone did. This is due to there being a higher calcium carbonate concentration per volume as the inclusions are removed during the metamorphism process. The expected result was that the marble would be more chemically inert – reacting slower and using more of the acid. This was proven to be the case. This may be used in deciding what building materials should be used. Limestone may not be so hard-wearing and may degrade faster in kitchen tiles or benchtops, for example. Having acidic foods spilt or exposed to the limestone may wear it down faster than the marble.
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False Positives in Blood Detection using
the Hemastix Text
By Katie Maddock
Blood detection methods can be used in a number of instances, but primarily in forensic applications. Hemastix are one of the most common presumptive tests that can be done – alongside the use of other crystal, catalytic and instrumental methods. Hemastix in particular produce a visible colour change reaction due to the peroxidase-like activity of the Heme being catalysed by the breakdown of hydrogen peroxide in the blood. Despite this, Hemastix have been known to produce false positive readings when testing substances other than blood, such as Horseradish, Tomato / sauce, and Red Onions. This experiment attempts to determine if there is a trend of substances that produce this false positive result and determine the cause. This question is investigated by testing these known false positives, as well as some unknowns. As well as this, the sensitivity of the Hemastix was investigated and a specific look was taken into a number of vegetables that fall into the Liliaceae and the Solanaceae family. The major findings of this experiment conclude that there are a number of substances in the average household that could be used to induce a false positive reaction.
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The Effect of Chitosan on the strength of
Starch-Based Bioplastics
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By Georgia Tapp
The vast dependency on petroleum-based plastics has led to a worldwide issue of mass accumulation of plastic waste and its responsible disposal. In addition, amassing of fish wastage has been increasing as a result of an advancing aquaculture industry, posing pollution issues to aquatic environments and coastal regions. With advancing technology, bio-based starch plastics that contain organic fish waste have begun to emerge. This research task used modified methodology to investigate whether an increase of organic fish waste increases the strength of a bioplastic, or if there is an optimum amount. Using online methods, brief reflections from previous works and many ‘trial and error’ experiments, the investigation was conducted. The results of this investigation found that, as the percentage of chitosan increased, so did the strength of the bioplastic. Reflective of the correlation between density and strength, as more organic fibres were present in the plastic, porosity was generally lower, and therefore strength is enhanced. The investigation favours that development and investment in this area could lead to the discovery of a traditional plastic alternative that better complements the environment and our exponentially growing population.
