This experiment demonstrated how to purify benzoic acid by means of recrystallization. The original benzoic acid solid sample used contained 5% salicylic acid, an impurity. Benzoic acid is of the following structure:
Salicylic is of the following structure:
For part 1, after boiling and dissolving benzoic acid in water, we allowed the solution to cool and recrystallize, first at air temperature and then on ice. As the solution cooled at air temperature, the benzoic acid started to recrystallize, with a rather gel-like appearance. As the solution cooled on ice, the benzoic acid further recrystallized, becoming more of a solid. Filtering the crystals by vacuum filtration separated the salicylic acid out from the benzoic acid, separating the
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After boiling and dissolving 0.993 grams of benzoic acid in 100 mL of water, we allowed it to again cool at air temperature and then on ice. However, this time, it did not crystallize at all as it cooled at air temperature. Although, on ice, the benzoic acid did end up with a small amount of crystals that formed on the bottom of the beaker. After filtering the salicylic acid from the benzoic acid, the remaining crystals of benzoic acid were in rather crumbled …show more content…
When we put the 0.1% ferric chloride with our solution from part 1, it did not visually change to a purple color. The spectrometer gave us a wavelength reading of 7 nm. When we put the 0.1% ferric chloride with our solution from part 2, there was a slight visual change in color, having a slight purple tint to it. The spectrometer gave us a wavelength reading of 4 nm. Since both parts of the experiment gave a wavelength reading greater than 0, this also indicates the presence of impurities in the recovered benzoic acid.
Post-Lab Questions:
1. From the trends in the data, seek to draw conclusions about the following variations in the procedure and how they affect the yield and the purity of the recovered benzoic acid.
a. a larger solvent volume, b. a smaller solvent volume, c. a more rapid cooling time.
I averaged all of the temperature ranges from the first part of the experiment and found this to be 107-113oC, with an average percent yield of
Solid triphenylmethanol (0.200 g, 0.768 mmol) and sulfuric acid (2 mL) were added to a reaction tube, which was then ground using a glass rod until it dissolved and turned a dark orange color. The mixture was then added dropwise via a glass pipette into another reaction tube containing methanol (1 mL). An extra amount of methanol (2 mL) was used to transfer the rest of the contents of the first reaction tube. Formation of crystals was facilitated by scratching the side of the tube and adding additional methanol until the color changed to an off-white color. The contents of the tube were then vacuum filtered with water and the resulting crude product was weighed and then recrystallized using hot methanol to form triphenylmethyl methyl ether (0.051 g, 0.186 mmol, 24.2%). The melting point was 81 – 83˚
The objective of this experiment was to perform extraction. This is a separation and purification technique, based on different solubility of compounds in immiscible solvent mixtures. Extraction is conducted by shaking the solution with the solvent, until two layers are formed. One layer can then be separated from the other. If the separation does not happen in one try, multiple attempts may be needed.
The general objective of this experiment was for the students to familiarise with the preparation of a simple organic compound and to purify the compound by recrystallization. This experiment allows the students to conduct synthesis of aspirin, reinforcing the skills of recrystallization and the technique of melting point determination.
Ensure gloves are worn at all times when handling strong acids and bases within the experiment of the preparation of benzocaine. 4-aminobenzoic acid (3.0g, 0.022 moles) was suspended into a dry round-bottomed flask (100cm3) followed by methylated sprits (20 cm3). Taking extra care the concentrated sulphuric acid of (3.0 cm3, 0.031 moles) was added. Immediately after the condenser was fitted on, and the components in the flask were swirled gently to mix components. It should be ensured that the reactants of the concentrated sulphuric acid and the 4-aminobenzoic acid were not clustered in the ground glass joint between the condenser itself and the flask. In order to heat the mixture to a boiling point, a heating mantle was used and then further left for gently refluxing for a constituent time of forty minutes. After the duration of the consistent forty minutes the rou...
Once the mixture had been completely dissolved, the solution was transferred to a separatory funnel. The solution was then extracted twice using 5.0 mL of 1 M
Afterwards, of the solution turning yellow, a white powder began to appear when all the water had disappeared. Now that, the solution had sixty- nine minutes to boil, the sodium hydrogen carbonate and the acetic acid produced sodium acetate. Figure 1. The equipment setup for both days, the picture was taken at the end of day one. Data
The acid contained such as malic and tartaric acid actually work to dissolve the
Keeping the resulting solution well stirred throughout the following titration. Started the titration by adding the acid in increasing of 0.5 mL. When the solution started to turn pink, I recorded this volume of strong acid as the endpoint and calculated the volume used in the reaction. And then I repeated steps 2, 3, 6 and 7 at two more times. Conclusion: We learned in our lab how to find the approximate endpoint of an acid-base solution and what the endpoint signified.
The sample was subjected to steam distillation as illustrated in Figure 1. A total of 50ml of distillate was collected while recording the temperature for every 5.0 ml of distillate. The distillate was transferred into a 250ml Erlenmeyer flask and 3.0 g of NaCl was added. The flask was cooled and the content was transferred into a 250-ml separatory funnel. Then 25.0ml of hexane was added and the mixture was shaken for 5 minutes with occasional venting. The aqueous layer was discarded and the organic layer was left inside. About 25.0ml of 10% NaOH was then added and the mixture was shaken as before. The aqueous layer was collected and then cooled in an ice bath. It was then acidified with enough 6.00 M HCl while the pH is being monitored with red litmus paper. Another 25.0 ml of hexane was added and the mixture was shaken as before. The hexane extract was saved and a small amount of anhydrous sodium sulfate was added. The mixture was then swirled for a couple of minutes then filtered. A small amount of the final extracted was tested separately with 1% FeCl3 and Bayer’s reagent.
When benzoic acid paired with 1.0 M NaOH, it was observed that both compounds were soluble. Upon the addition of 6.0 M HCl into this solution, benzoic acid became insoluble. Benzoic acid was also insoluble in 1.0 M HCl. Ethyl 4-aminobenzoate was found to be insoluble in 1.0 M NaOH and soluble in 1.0 M HCl. But then, after adding 6.0 M NaOH into the test tube C (mixture of ethyl 4-aminobenzoate and 1.0 M HCl), a white powdery solid (undissolved compound) was formed. These demonstrate that both the acid and base became more soluble when they were ionized and less soluble when they were
When the reagents (Aniline and Acetic anhydride) were initially added to the flask, the crude product of acetanilide started to form, along will a small number of impurities. As the compounds were mixed the solution turned a pale-yellow color, with white crystals of acetanilide forming in the solution as the reaction proceeded. As the solution began to heat up the crystals dissolved because the energy (as heat) was being added to the molecules of liquid causing separation between the pure Acetanilide and impurities in solution. The charcoal was then added to bond to the impurities in the solution, separating them from the Acetanilide, and ensuring they would not recrystalized as the solution was cooled. The solution was then left to return to room temperature, and the acetanilide became purified pure crystals, while the impurities remained in the solution and were filtered out. The final product was flaky white crystals of
To the first Erlenmeyer flask with the ferrous salt add about 1/3 of the 0.75N sulfuric acid. Dissolve the salt by gently swirling it in the dilute acid. Add about 5mL of the Zimmerman-Reinhardt Reagent (this reagent contains phosphoric acid which complexes yellow ferrous ions into colorless compounds which do not obscure the endpoint; it also contains manganous ions which inhibit the oxidation of any chloride ions in the sample). The use of a white background underneath the flask aids in the detecting of the endpoint. Repeat with second sample.
Recrystallization is a common technique used for purifying an impure compound within a solvent. This method of purification is based on the principle that the solubility of most solids increases with higher temperature. For this type of purification, an impure compound is first dissolved to prepare a highly concentrated solution at a high temperature. Following this the solution is cooled, which drops the temperature and causes the solubility of the impurities in the solution, along with the substance being purified, to decrease. The impure substance then crystallizes before the impurities, leaving them behind in the solution. The slower the cooling, the bigger the crystals that will be formed. Finally, a filtration process must be used to isolated the purer crystals from the less pure ones. Solubility curves can also be used in order to predict the outcome of a recrystallization procedure.1
If the solid dissolved in the solvent at room temperature, then it was too soluble and that solvent could be eliminated. The acetanilide is completely dissolved in ethanol and dichloromethane, therefore eliminating them from being the suitable solvent. If the solid did not dissolve at room temperature then it was placed in the sand bath and left to boil. If the solid dissolved, it was placed in the ice bath and if crystals were observed coming out of the solution then the suitable solvent was found. The suitable solvent was water as the crystals came out once placed in the ice bath.
Food industry especially canned food usually implements knowledge of organic chemistry in their production. Appropriate usage of chemicals will kill microorganisms or stop their growth. Chemical food preservatives are those substances which are added in very low quantities (up to 0.2%) which do not alter the organoleptic and physico-chemical properties of the food or may only bring minute effects.Sodium benzoate is one of the food preservative that is widely used and it can be found in many foods and soft drinks (Lennerz, 2015).Furthermore, in alcohol industry, the production of ethanol can be increased by altering the chemical reaction of certain hydrocarbons group or adding catalyst in fermentation process. These methods do not only reduce the cost of production but also increase the speed of production. Besides that, food colouring is one of the inventions of organic chemistry in food and beverage industry. Colour is added to replace colour loss during processing, to enhance the existing colour, minimize batch variations and to color otherwise uncoloured food (Dr M Madhava Naidu, 2013). Food flavouring used in food processing also improves the food economic value. The amino acid’s sodium salt, monosodium glutamate (MSG) is one of the most commonly used food enhancer in food processing.The major components of most flavours and fragrances are a class of compounds known as