Provide Evidence in a Prosecution Case :: science

Provide Evidence in a Prosecution Case Experiments to Provide Evidence in a Prosecution Case with the Pervis Vinegar Company on Unknown Toxins The aim of this experiment is to preform tests on two samples of vinegar, one that is commercially safe and the other not (from the Pervis Company) to determine the unknown toxin contained in the Pervis Vinegar. Materials: * Numerous Beakers/Conical Flasks * Phenolphthalein Indicator * Burette * Numerous Test Tubes * Sticky Tape * Test Tube Rack * Sodium Hydroxide (NaOH) * Calculator * Sample of Commercially Safe Vinegar * 2 Surgical Swabs (large cotton bud) * Sample of Pervis Vinegar (Toxic) * 2 Agar Gel Plates * Universal Indicator * Incubator Oven * Incubator * Bunsen Burner * Water * 2 Small Syringes * Potassium Chromate Solution * Hydrochloric Acid Methods To fully determine and identify the unknown toxin present in the Pervis vinegar sample, four tests were needed. A molarity test was completed, a sample of the vinegar was then allowed to grow on an agar plate to ascertain whether bacteria were present and a pH test would also be done. The final test was a precipitant test to discover if the heavy metal Lead was present in the Pervis sample. A titration experiment was now set up using Sodium Hydroxide solution as the alkali in the burette with a molarity 0.01177 and 25ML of Pervis vinegar was placed in the beaker underneath the burette. Approximately four drops of Phenolphthalein indicator where added to the Pervis vinegar and then the measured amounts of NaOH were slowly added to the vinegar. The burette needed to be refilled several times and the average amount of NaOH solution needed to neutralise the Pervis vinegar was 181.5 ML. That same experiment was then tried using commercially safe vinegar in the beaker below the burette. Four drops of Phenolphthalein indicator were again placed in the vinegar and then measured amounts of NaOH were released from the burette into the beaker. This was completed three tines with the average NaOH needed to neutralise the safe vinegar approximately 154.5 ML. These amounts for the NaOH added were then recorded for later analysis. The pH test was now done with both samples of vinegar. Two test tubes were placed in a test tube holder and 14ML of each sample of vinegar poured into one of the test tubes. About two drops of Universal Indicator were placed in the test tubes and the reaction colourers were recorded for later use.