The substitution reaction was successful but not fully effective. 19. If the data was inconclusive, then comparing various compounds and the unknown based on physical characteristics would be the first step, titrations would also be a good method. 20. To get a better yield, redoing the experiment would require careful attention in the recrystallization steps: amount of solvent used, how hot solvent is, if the mixture cools to room temperature before placing it in an ice
The purpose of this experiment was to identify two unknowns and their ratios in a given mixture. The identities of the unknowns were two of either acetone, methanol, hexane, cyclohexane, heptane, toluene, or ethyl benzene. Distillation Distillation is used to remove impurities from a mixture – one component of which must be a liquid. Boiling points are utilized in determining the identity of the unknowns. Types of distillation include
Separation of Liquids by Fractional Distillation and Analysis by Gas Chromatography Methods and Background This lab was exceptionally knowledgeable and important in order to understand how certain compounds can be separated based on their boiling points (Landrie, 43). This experiment in particular focuses on understanding the separation of 1:1 mixture of acetone and 1 propanol using the method of fractional distillation (Landrie, 43). In the previous experiment, we focused on understanding the same separation but in terms of simple distillation. If compared with the data shown below with the data in the previous experiment, overall, the fractional distillation showed better and more effective results (Landrie, 43). This experiment also provided better
I believe that it is not common to obtain an exact 100% yield because that would mean that the chemists doing the experiment would have to do everything perfectly without any flaws. Like measuring off by a slight amount or leaving behind some of the substance if transferring it over to another flask or beaker. A person could not do something so perfectly because humans always do errors while doing things, it would be very unlikely for a chemists to get a 100% yield after for a chemical reaction. 6. The percentage yield was not 100%.
The temperature in our experiment was not very high which didn’t result in denaturation of peroxidase. The temperature seemed to be a constant that didn’t affect the experiment. If the temperature was higher in pH 3 and low in pH 10, then it would cause pH 3 to denature even more which would make the pH 3 total about 4.0. Substrate concentration basically means the amount used for the substrate. The substrate in our experiment was 0.1% hydrogen peroxide.
In this lab, human error could have possibly been that the salt wasn’t fully dissolved or even the Kool-Aid wasn’t fully dissolved. To fix this next time, both mixtures can be stirred a little longer. A third human error could have been when putting 20 drops into the test tubes, some drops were bigger than others causing there to be more than mL of mixture in the test tube. At the end of the lab, a red and yellow M&M were used to do a home material test. I dissolved the color off the shell with warm water and placed a dot of each color onto a strip of chromatograph and placed them in two individual
Resistance happens when a drug is no longer effective in controlling a medical condition. Resistance arises for many reasons, for example the effectiveness of barbiturates (used to cure mild seizures and sleep disorders) often decreases when used repeatedly because taking it repeatedly causes the body to increase its production in the liver of mixed function oxidases that metabolise the drug, therefore reducing the drug’s effectiveness. An increase in the rate of production of an enzyme that metabolises the drug is a common reason for drug resistance. Another reason for drug resistance is the down-regulation of receptors (decrease in the number of receptors).
Excess or lesser amounts of 1.00 M NaOH can lead to inappropriate standardization. Consequently, an incorrect standard solution prepared yielded to the wrong number of moles of NaOH which consequently give us wrong data. Another issue arose with the amount of the indicator used. Since drops are the measurement associated with the amount of phenolphthalein, it is quite difficult to obtain an accurate amount. A slight error in the indicator can shift the endpoint and consequently affects the volume of the obtained NaOH.
If you conduct the catalyzed decomposition of hydrogen peroxide in a closed vessel, you will be able to determine the reaction rate as a function of the pressure increase in the vessel that is caused by the production of oxygen gas. If you vary the initial molar concentration of the H2O2 solution, the rate law for the reaction can also be determined. Finally, by conducting the reaction at different temperatures, the activation energy, Ea, can be calculated as heat is the energy source. Catalase is very efficient at decomposing hydrogen peroxide; one molecule of the enzyme can catalyse the conversion of over 6000,000 hydrogen peroxide molecules into water and oxygen every second. The enzyme occurs widely in tissues such as the liver and prevents accumulation of, and tissue damage by, hydrogen peroxide that is produced during metabolism.
The product (Cu(OH)2) was unstable and could reform Cu2+ and OH- ions due to its high solubility. This result can cause difficulties on separating Cu from the other metals in the AMD. Therefore, additional treatment, such as sulfidization, is required to prevent the occurrence of the reformation process
My group recorded higher heart rate compare to the class average when we used caffeine on the Daphnia as seen in Figure 2. Several errors could have accounted for this data. This including perhaps the Daphnia’s heart rate may have changed because of fear while being moved from the bowl to the microscope slide. Another possible error could have also been the amount of time that it took to change the solutions, which could have accounted for slight variations in heart rate. Temperature is yet a further error to account for as the microscope slide temperature was constantly changing to view the specimen, and change the dosage of caffeine or alcohol.
Besides the inaccuracy in determining the freezing point and problems in the enthalpy of dissolution, the largest source of error was the temperature probe. Over the course of the multiple trials, the temperature probe would read somewhat inconsistent values. Due to this uncertainty, trials were performed on pure deionized water to see how far the probe read from zero degrees Celsius. Another source of error was in the calorimeter. Using two foam cups as a calorimeter is sufficient, although far from perfect.
Another reason as to why I suggest this is because tap water may have other substances or little things mixed, which may cause an inaccurate reading of the mass which will cause an error in density, so it is better to use pure water. Finally, temperature may play a big role in this as well. The accepted room temperature would the density of 1g/mL is 21°C. If the room temperature is measured, then it can be considered that there will be a change in density due to an increase or decrease in the average room
Experimental Clay-catalyzed dehydration of cyclohexanol Cyclohexanol (10.0336 g, mmol) was added to a 50 mL round bottom flask containing five boiling chips, Montmorillonite K10 clay (1.0430 g) was then added to the cyclohexanol and the mixture was swirled together. The flask was then placed in a sand bath and attached to a simple distillation apparatus. The contents of the flask were then heated at approximately 150 °C to begin refluxing the cyclohexanol. The distillation flask was then loosely covered with aluminum foil and the hood sash was lowered in order to minimize airflow. As the reaction continued, the temperature was adjusted in order to maintain a consistent rate of distillation.
Introduction The purpose of this lab was to compare simple distillations of two sets of liquids by graphing the boiling points. One set of simple distillation of two liquids were supposed to have a boiling point difference of bout 30C while the other set of simple distillations had a melting point difference of about 57C. Furthermore, by conducting this experiment, students would develop a better understand of distillation and gas chromatography. Furthermore, I hypothesized that cyclohexane and p-xylene distill better than cyclohexane and toluene since cyclohexane and p-xylene have a larger boiling point difference than cyclohexane and toluene. The boiling point of cyclohexane is 80.74C while the boiling point for p-xylene is 138.23C and the boiling point for toluene is 110.6, thus