As mentioned in number 13, the data for the melting point makes sense because my pure product and given compound almost perfectly matched. 17. Again as explained in number 14, the TLC data made sense because my pure compound and 4-tert-butylbenzyl phenol had similar distances from the solvent origin of the plate. The presence of benzyl bromide and benzyl alcohol also explains how not all the product dissolved in the filtrate. The possible explanations and changes to make are similar to the previous questions.
But the difference was no bigger than 0.08, and after the values were rounded the same empirical formula was deduced. So the experiment can be concluded as successful. Evaluation: The method used was simple and easy to follow; however, it did not include how much oxygen was needed to react completely. Also it didn 't mention what magnesium oxide looked like after it finished reacting, so it was a guesswork of determining whether the reaction was finished or not. The data was handled accurately, values clearly labeled and calculated in the correct procedure.
For example, dopamine has a Km of 95 and a Vmax of 11 x 105. Both of these values are fairly high and would not make an effective substrate for catechol oxidase since the enzyme has a low affinity for the substrate. An example of a good alternative substrate would be 4-methylcatechol that has a low Km of 1.1 and a Vmax of 3.4 x 105. The enzyme now has a high affinity for the substrate and therefore requires less substrate to meet its Vmax. The substrate for the sweet potato catechol oxidase is N-phenylthiourea.
The pKa of this unknown weak acid is 4.0 and the Ka is 1.0 x 10-4 mol dm-3 while the molecular weight is 166.67 g mol-1. It is closely related to the ascorbic acid with a pKa of 4.10 and a Ka of 7.9 x 10-5 with a molecular weight of 176.12 g mol-1. Therefore it can be concluded that the unknown acid is ascorbic acid. Titration technique is best suited for this experiment because the end point and equivalence point can be distinguished by the physical changes which are the colour change of the mixture. We are also able to better control and determine the volume of NaOH in the burette needed to neutralise HCI, CH3COOH and the unknown acid.
Similar result were investigated earlier related to Perkin reaction of Quinone, . When 2, 6-dimethoxy-p-bezoquinone treated with propionic anhydride in presence of sodium propionate gives a mixture of condensed product (12) and (13) Scheme-6 Although, when the same reaction is carried out in milder condition, the product (14) is isolated and it can be converted to 12 &13 in Perkin condition. It is observed that (14) may be in equilibrium with dimethoxybenzoquinone and methyl ketene. The isolation of product (14) does not prove that the product (14) is the reaction intermediate of product (12) and (13). So, we can conclude that the mechanism of the Perkin reaction is not as simple as indicated in Scheme-(2a&b).
The only difference from normal phase is that the column now is modified in order to attach long hydrocarbon to it surface. When a polar solvent is used strong attractions between the polar solvent and polar molecules in mixture being passed through the silica. Polar molecules will spent most of the time moving with the solvent because there will not be as much as attraction between the hydrocarbon chains attached to silica and the polar molecules in the solution. About the non polar mixtures, because of the Van der Waals forces will tend to form attractions with hydrocarbon
This was proved by utilizing the IR spectrum to verify the C=O was not in the final product as it lacked the 1640 cm-1 peak. The melting point of 113-115 degrees C proved that the final product obtained was the E-Stilbene. The TLC plate proved that the E and the Z product was produced, show cased by the double intensity of the DCM spot to the final product’s spot, both which had an Rf of 0.92. The double intensity proved that both products were produced, but through heating and filtering, the Z-Stilbene was
The prices for a bottle may vary due to various reasons such as strength, brand names, or even the consistency, such as tablets or gummies. The problem here is that there are so many types of antacids at a variety of prices however, how effective the tablets are tends to be unknown. Due to this, the purpose of this lab is to assist consumers in deciding which type of antacids to buy based on the cost and how effective the tablets are at neutralizing the acid found in the stomach. This will be found by performing two different titrations where the antacid will first be reacted with hydrochloric acid and then this will be reacted with sodium hydroxide. It is hypothesized that the Life Brand bottle of antacids will be the most cost-effective because it is the cheapest bottle and it claims to have the same amount of tablets as the Tums Regular Strength with the same amount of calcium carbonate per tablet as the
As you can see from my sample that our aspirin sample contains a small amount of pure aspirin and a lot of salicylic acid. Therefore this means that my sample wasn’t pure as it still had remnants of salicylic acid which suggests to me that the reaction hadn’t been fully completed, however my sample did contain a small amount of pure aspirin which means that the reaction is partially had taken place. The sample would have been pure if there was no salicylic acid on the card then my sample would match the pure aspirin sample which means there would have been a fully completed reaction. 2. State what practical techniques used during the procedure and explain how they influence the purity of the sample.
Determination of the rate law and activation energy of a chemical reaction requires a number of steps. By varying the concentrations of reactants in the iodination of acetone it was determined that the reaction is first order with respect to both acetone and hydrochloric acid concentration and zero order with respect to iodine concentration. The error in all parts of this experiment is relatively small. This reaction is fast enough to be performed in a reasonable amount of time, but not so fast that it is difficult to duplicate this
By looking at our results, even though my partner and I didn’t obtain a high percent recovery for the unknown, we were still able to identified our unknown to be Acenapthene. We know that our unknown B8 is Acenapthene because of its melting range and its color. The unknown B8 was similar to the color of Acenapthene, and the mixed compound (Acenapthene and the recrystallized compound)’s melting range was close to Acenapthene’s literature melting range. With these two points, my partner and I believed our unknown B8 to be Acenapthene. According to our recrystallized vanillin, we know that our vanillin was pure because of its melting range.
During plating, drops of the Excedrin solution may have been introduced to the plate. Also, the capillary tube may have been contaminated. This lead to nearly identical marking on the TLC plate and similar Rf values. Due to this, it is not possible to conclude whether or not acetaminophen was separated from the sample of Excedrin. The Rf value of the pure isolated caffeine was 0.28.
In order for a substance to be pure, its melting point, from start to finish, must stay within 3 oC or 4 oC because more pure organic substances melt within the range of 1 oC – 2 oC. (Craine et al., 2012) The range of the crude was 5.3 oC, a clear indication of impurity. In addition, it was well below the literature melting point of 9,10-dihydroanthracene-9,10-α,β-succinic anhydride at 262 oC – 264 oC, which was another indication of impurity. However, the pure product had a melting point of 260.3 oC – 263.9 oC, which was much closer to the melting point of the pure product and stays within the range of 3 oC – 4 oC, which could indicate that there was still a small amount of impurity, but the product attained was close to a pure