acid and a few drops of conc. sulphuric acid. Pour into water. | (i) Litmus turns red and a white precipitate with silver nitrate(aq) (drop on end of glass rod)‚ if the mixture is poured into water you may detect a ’pleasant’ ester odour‚ can test for HCl but water and amines produce it too!(ii) as for (1) but no ester smell!(iii) You should get a ’pleasant’ characteristic smell of an ester. | (i) R-OH + CH3COCl ==> CH3COOR + HClAn ester and hydrogen chloride are formed(ii) R-OH + PCl5 ==> R-Cl + POCl3 + HCla
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The purpose of the unknown bacteria lab assignment was to select an unknown bacteria culture and‚ through a series of metabolic tests‚ identify which bacteria genus resided in the pure culture received. A nutrient broth inoculated with bacterial culture (numbered 45‚ henceforth referenced as U45) was selected and a streak plate was made to isolate a pure culture for use throughout the assignment. From the streak plate‚ several slides were made to determine the morphology of unknown 45. A Gram stain
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contents of each of the flasks T3 to T7 were titrated and a starch was used as an indicator. All the obtained results were recorded in a table. A graph of the titres of sodium thiosulphate versus time from the start of the reaction was plotted from which the order of reaction with respect to iodine was deduced. Method 2. Determining the rate of a reaction with respect to iodine Using the burettes the four mixtures of hydrochloric acid (HCl)‚ propanone (CH3COCH3) solution and water were made up in
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found in saliva that acts on starch to begin the digestion process (Stick and Williams‚ 2009). Amylase acts on starch by breaking off maltose (C12H22O11) molecules from the end of starch chains (Di Giuseppe‚ 2002). Every time a bond is broken in a starch chain‚ a water molecule is consumed. This process is referred to as a hydrolysis reaction which requires water to digest a substrate‚ in this case starch (Walsh‚ 2002). Phosphorylase is also an enzyme that acts on starch by removing glucose molecules
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ions in water - acids – sour‚ turn blue litmus to red (pink)‚ conduct electricity - bases – bitter‚ soapy taste‚ slippery‚ conduct electricity‚ turn red litmus to blue Bronsted – Lowry Theory: - acids – donate proton‚ bases accept proton - ex: HCl donates proton to water ( not reversible ) - ex: water donates proton to ammonia – reversible - Amphoteric substances: ____________________________________________________________ - Advantage of B-L definition: - 1. reactions can be identified as
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cofactors for activity Classified according to the types of reaction they catalyze – Oxidoreductase – Transferase – Hydrolase – Lyase – Isomerase – Ligase Page 6 Page 7 Amylase An enzyme that breaks down starch into oligosaccharides through hydrolysis Secreted by the human’s parotid glands and the pancreas α-Amylase β-Amylase γ-Amylase Page 8 Factors that may affect catalysis rates Temperature pH Enzyme concentration Amount of substrate
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calcium sulfide d) aluminum hydroxide e) mercury (II) phosphate f) tetraphosphorus trisulfide g) nitrous acid 7. Which of the following is not an example of a chemical change? a) converting gasoline to carbon dioxide and water b) digesting starch to give glucose c) grinding sucrose crystals into powdered sugar d) smoking tobacco e) generating carbon dioxide from baking soda and vinegar 8. The density of ethyl alcohol is 0.789 g/mL. What is the volume of 35.5 grams of ethyl alcohol
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Principle involved | Dehydration of the carbohydrate by concentrated sulfuric acid to produce an aldehyde | Reagent | H2SO4 | Positive results | a purple-black layer/violet ring in the compound | Compound responsible | | | | Amylose in starch is responsible for the formation of a deep blue color in the presence of iodine. The term carbohydrate originally referred to hydrates of carbon because the general formula of these compounds was CnH2Non or Cn(H2O)n. SAMPLES | OBSERVATIONS
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to see if there was a clearing. After doing some research‚ it was shown that B. subtilis is lipase positive so there should have also been some clear sones like the Staphylococcus aureus (Watson). The DNAse agar could not have been analyzed because HCl was not available to precipitate the DNA to see if the bacterium had the enzyme DNase. If the test could have been analyzed‚ Staphylococcus aureus would be positive for DNase and E. coli would have been negative (DNase
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Isolation and identification of an unknown bacterium Pillay‚ Esmerelda (209504371) School of Biochemistry‚ Genetics and Microbiology Department of Microbiology University of Kwa-zulu Natal 25 October 2010 ABSTRACT Different types of bacteria in various forms are found all around us‚ and it is a microbiologist’s job to be able to identify these bacteria. Using various staining techniques and physiological tests‚ an isolated bacterium can be identified. In this experiment‚ a single bacterial
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