In this lab experiment, three milliliters of pure cyclohexane was placed within a test tube and lowered into an ice-water bath. The test tube had a temperature probe within it, which measured the cyclohexane lowering in temperature. Once the cyclohexane solution started to solidify, the cooling curve could be observed and the freezing temperature could be determined. The pure cyclohexane was then thawed, with 0.60 grams of biphenyl being added to the cyclohexane. The experiment was then run again. The result was a freezing point of around 8.6℃ for the pure cyclohexane and 7.0℃ for the cyclohexane-biphenyl solution. To confirm the results that the cyclohexane-biphenyl solution had a lower freezing point, the experiment was ran again. The results
Craig, D. Q. (2002). Pharmaceutical Applications of Micro-Thermal Analysis. Journal of Pharmaceutical Science, 91(5), 1201-1213.
2. Put a few ice cubes in one beaker of water and wait until it is 16 °C to remove them
After researching this, I took the distilled frozen water I had frozen, and mixed it with distilled cold water. I mixed the two together and let them set. I then took the thermometer that I was calibrating, and recorded the temperature. I watched the thermometer drop from about 60°C all the way down to -1°C after it completely stopped moving. I took the thermometer out, recorded what I saw, and repeated this two process two
The goal of this experiment was to convert 2-methylcyclohexanol into 1-methyl-1-cyclohexene, 3-methyl-1-cyclohexene, methylenecyclohexane, and water through the addition of phosphoric acid and sulfuric acid. This was done through distillation where a mixture of 2-methylcyclohexanol, phosphoric acid, and sulfuric acid was distilled for 30 minutes in a reflux apparatus. Sulfuric acid being a strong acid acts as a catalyst in this reaction. Phosphoric acid also acts as a catalyst in this reaction. The distillate was then added to a centrifuge tube along with 1-2 ml of saturated sodium chloride. The bottom layer in the centrifuge tube was then extracted and dried using anhydrous sodium sulfate. This bottom layer was then distilled again in
The unknown bacterium that was handed out by the professor labeled “E19” was an irregular and raised shaped bacteria with a smooth texture and it had a white creamy color. The slant growth pattern was filiform and there was a turbid growth in the broth. After all the tests were complete and the results were compared the unknown bacterium was defined as Shigella sonnei. The results that narrowed it down the most were the gram stain, the lactose fermentation test, the citrate utilization test and the indole test. The results for each of the tests performed are listed in Table 1.1 below.
Because the frozen water molecules in your steak, ice cream, or bag of corn want to find the coldest place they can, which typically isn’t inside
Product C did the best at lowering the freezing point of the water. We know this by studying the results of our lab, directly after all the other substances activated in the water work product C immediately sent the temperature from 20 degrees celsius to 0 degrees celsius in 30
The purpose of this experiment was to make a conclusion on why Mr. R’s lawn was turning yellow, and dieing around his drainage pipe. In this experiment there were different lab groups that tested out different chemical products, that would be washed down a drain. There was a wide assortment of products that were tested in this experiment, for example, windex was one of the products being tested. On our experimental days, we would take our product, and add it to the water supply of our grass. My lab group experimented with windex. Our hypothesis was, if windex was added to the daily water supply of grass, then the grass will turn yellow and die because of the chemicals in the windex.
Acid-base liquid-liquid extraction was done to separate the individual components of Excedrin so that caffeine could be extracted. Acid base liquid-liquid extraction works by converting an acid or base to the alternate form by adding a strong acid or base, which allows it to become more polar and move between solvents. The solvents can then be extracted off, allowing for the individual components to be extracted. This is important for organic chemists, because being able to separate components allows for reactions to take
The stunning amount of diversity found in antifreeze proteins is evident of a fascinating evolutionary story. Exploring the phylogenetic and molecular data from different species of cold-water fish is a common starting point for determining the origins of antifreeze proteins. Antifreeze proteins can be divided into two groups, the AFPs and AFGPs. Of the AFPs, there are currently four known types: I, II, III and IV (Cheng et al., 1998). By examining...
In this experiment, Column Chromatography was used to separate and purified a mixed sample of Fluorine and Fluorenol. This was done by relying on this differences in polarity. Because of OH group present in the Fluorenol, that makes this substance much more polar, which cause it to move down the column at a much slower rate. After the procedures were done, the solution was collected into 13, 3 mL vials. By using TLC, the different compounds were separated and combined. Fractions #1-3 contained Flourine, #4-10 contained Fluorenol, and #11-13 did not show any significant signs of either compound. The lower determined Rf values for Fluorenol indicated that it was a more polar substance that Fluorine. Out of the beginning amount of 0.0680 grams
Alcohol, which is the nucleophile, attacks the acid, H2SO4, which is the catalyst, forming oxonium. However, the oxonium leaves due to the positive charge on oxygen, which makes it unstable. A stable secondary carbocation is formed. The electrons from the conjugate base attack the proton, henceforth, forming an alkene. Through this attack, the regeneration of the catalyst is formed with the product, 4-methylcyclohexene, before it oxidizes with KMnO4. In simpler terms, protonation of oxygen and the elimination of H+ with formation of alkene occurs.
Icing is normally encountered in when the temperatures range between 14 to 32 degrees Fahrenheit...
The temperature probe was placed into the test tube and recorded the temperature of the freezing solution using Logger Pro software. The test tube was held against the inner glass of the ice bath beaker so the test tube was visible to see when the solution froze over. Once the freezing point was measured, the temperature stopped being monitored and the data was recorded. The steps mentioned above for finding the freezing point, also known as ΔTf, was replicated for the 0.0, 0.4, and 0.6 concentrations. To find the freezing point depression, the equation ΔTf = imKf was used. The molality (m) of each solution was then calculated dividing moles of solute by kilograms of solvent, and the Kf value for magnesium chloride is known to be -1.86. Since magnesium chloride breaks down into three ions in deionized water, it was concluded that the Van’t Hoff factor couldn’t exceed three. For better accuracy, the experiment explained above for finding the freezing point depression and Van’t Hoff factor was re-conducted exactly the same to determine more accurate results. Again, the molality of each solution was calculated, and a graph expressing the change in freezing temperature verses molality
Introduction: A phase change is a result from the kinetic energy (heat) either decreasing or increasing to change the state of matter (i.e. water, liquid, or gas.) Thus saying, freezing is the phase change from a liquid to a solid which results from less kinetic energy/heat. Also, melting is the phase change from a solid to a liquid which results from adding kinetic energy/heat. So, the freezing and melting point of something is the temperature at which these phase changes occur. Therefore, a phase change will occur when a vial of 10 mL of water is placed into a cup of crushed ice mixed with four spoonfuls with 5 mL of sodium chloride for 30 minutes. If 10 mL of water is placed in an ice bath, it will then freeze at 5 degrees Celsius because the kinetic energy will leave quicker with the ice involved. The purpose of this lab is to observe what temperature the water must be to undergo a phase change.