The next test used the test tubes labelled “cold” and , one again using a piece of liver and five milliliters of hydrogen peroxide with both being placed in the ice bath, both held vertical with a test tube clamp. After five minutes were up using a timer, the two tests were conducted. The test involving the boiling water had five milliliters of hydrogen peroxide poured into it. Meanwhile, the five milliliters of hydrogen peroxide was poured into the test tube labelled “cold”. After both tests, explanations were made about the
Results Figure 1. Effect of temperature on the reaction rate between catalase and H2O2 Figure 1 shows that the optimum temperature for catalase to catalyze hydrogen peroxide is around room temperature (30℃) as it has a very fast reaction rate (5). The overall trend is that temperatures that differ from 30℃, will decrease the reaction rate. Discussion This experiment supported the hypothesis, since catalase was the most effective with hydrogen peroxide when it was in an environment with a temperature of 30℃. It was expected that an extreme temperature would decrease the rate of reaction and results observed support that idea.
This was displayed in table 1, where the final temperatures of the water are lower compared to the initial temperatures, showing that the potassium chloride took heat energy away from the 20 mL of water. Endothermic deicers work slower than exothermic deicers, because endothermic deicers require warmer temperatures to dissolve, which makes them inferior when environmental temperatures are very low. Additionally, exothermic deicers will release energy as heat when the compounds dissociate, consequently, melting snow and ice faster.4 Furthermore, when comparing the enthalpy of dissolution of potassium chloride to magnesium chlorides value of -270, the most exothermic value in table 2, potassium chloride is shown to be a significantly worse deicer. Magnesium chloride being notably exothermic means that the compound can dissolve at low temperatures and releases copious amounts of heat
This is due to the boiling points of the two compounds are too close for an effective simple distillation. A simple distillation only works when the boiling points of the two compounds are separated by at least 50 °C (CITATION). Meanwhile, the boiling points of the compounds of the mixtures are 82.3 °C for 2-pronanol and 117 °C for 1-butanol (National Center for Biotechnology Information). As well, while fractional distillation is more difficult due to the added fractionating column and insulation, it allows for better separation and condensation of the individual compounds. This ensures that only the compound with the lower boiling point is completely condensed before the compound with the higher boiling point begins to condense.
There was an increase in temperature after the concentrated sulphuric acid was added into the volumetric flask containing the iron (II) solution, the outer glass of the volumetric flask was warm. The reason why concentrated sulphuric acid was added is so that the iron (II) solution is stabilized. This is because Iron (II) is vulnerable to be oxidized but the oxidation of iron (II), 〖Fe〗^(2+) to iron (III), 〖Fe〗^(3+) is unable to take place in the presence of an acid. Sulphuric acid which is a strong acid will react with potassium permanganate solution, which is an oxidizing agent, to produce high concentration of hydrogen ions in order to convert oxygen from the potassium permanganate solution into water molecules. Therefore, diluted sulphuric acid was added to the standard iron (II) solution before titration took place.
How does the temperature of water affect the appearance of the Mpemba effect? Introduction Context: The Mpemba effect is a hypothetical effect that stipulates that the hot water will freeze faster than cold water. The effect was first noted by Aristotle : “The fact that the water has previously been warmed contributes to its freezing quickly: for so it cools sooner. Hence many people, when they want to cool water quickly, begin by putting it in the sun.” Later on, the effect got its name from a Tanzanian student, Erasto Mpemba, who observed that hot water sample cooled faster in the freezer than the sample of cold water. There is a variety of conflicting research, and some of the researchers say that the Mpemba effect does not exist , and some researchers say that it does .
The upper oil layer was the crude BD and the down layer was crude glycerol. The crude BD was washed with warm water and was subjected to a heating under vacuum to eliminate excess methanol and water. The alkali catalyzed process included four levels of methanol to oil ratio, 3, 6, 8 and 10; Five levels of catalyst (KOH), 0, 0.5, 1, 2, 3 (%, w/w, oil), four levels of reaction time, 30 min, 60 min, 3 hour, 10 hour. 2.4. Esterification
The wax melted first, followed by the salt, and lastly the sugar. The salt not only burned before the sugar, but developed a brown color throughout most of the substance at a faster pace. In the water solubility test, the salt dissolved in the water, as soon as it was properly mixed and the sugar dissolved in the water as well, but was stirred for a longer period of time until it was completely dissolved. The wax did not dissolve in the water, however bits of the substance broke off from the main piece. With this information, the final results included: wax as a nonpolar covalent compound, since the substance melted first and was not soluble in water; salt as a polar covalent compound, since the substance was soluble in water and the second to melt; and sugar as an ionic compound because the substance melted last and was soluble in