...Chemistry 1B Experiment 16 77 16 Qualitative Analysis Introduction The purpose of qualitative analysis is to determine what substances are present in detectable amounts in a sample. This experiment has two parts. In the first part, you will analyze an unknown solution for the presence of seven common ions. In the second part, you will test an unknown solid to determine which of two possible identities is correct. Part I. Spot Tests for Some Common Ions A simple approach to the qualitative analysis of an unknown solution is to test for the presence of each possible ion by adding a reagent which will cause the ion, if it is in the sample, to react in a characteristic way. This method involves a series of “spot” tests, one for each ion, carried out on separate samples of the unknown solution. The difficulty with this way of doing qualitative analysis is that frequently, particularly in complex mixtures, one species may interfere with the analytical test for another. Although interferences are common, there are many ions which can be identified in mixtures by simple spot tests. In this experiment we will use spot tests for the analysis of a mixture which may contain the following commonly encountered ions in solution: CO32– SO42– PO43– SCN Cl – – carbonate sulfate phosphate thiocyanate chloride acetate ammonium C2H3O2– NH4+ 78 Chemistry 1B Experiment 16 The procedures we involve simple acid-base, precipitation, complex ion formation or oxidation-reduction...
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...Khanh Nguyen Thanhthao Vo September 17, 2014 RECRYSTALLIZATION INTRODUCTION The purpose of this experiment is to study how to perform recrystallization technique in order to purify compounds and to apply TLC and melting point detection technique to test the purity of the recrystallized sample. In chemistry, recrystallization is the purification technique for solid compounds, using an appropriate solvent, to coax out either the desire compound or the impurities. The name “recrystallization” is given because of the crystals often formed when the experiment is successfully performed.2,3 Recrystallization works based on the difference in solubility when the temperature changes. Therefore, picking the solvent to dissolve the compound is a very tricky and important part. For single-solvent recrystallization, which is performed in this experiment, the chosen solvent should not dissolve the sample while cold, so that the crystal can be formed when the temperature drops. However, the solvent should dissolve the sample completely while hot in order to release all the impurity crystals being trapped up in the solid form of the desired compound. Furthermore, the impurities should have higher solubility than the desired compound in that chosen solvent, so that all the impurities would remain in the solution while recrystallization takes place.2,3 In case no single solvent can be found, a system of two solvents can also be used for recrystallization. Generally speaking, in this solvent pair, one...
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...Synthesis of Acetanilide and Purification by Recrystallization Par, B., Ramos, S., Reynaldo, H., Roque, P., Servidad, Y., and Soriente, P. 2D-Pharmacy, Group No. 7, Department of Pharmacy, Faculty of Pharmacy, University of Santo Tomas, España Boulevard, 1015 Manila, Philippines Abstract Recrystallization is the primary method of purification used to isolate organic compounds in a supersaturated solution by the difference of solubility at different temperature that results to the separation of the compound from the solution. The purpose of this experiment is to synthesize acetanilide by the acetylation of aniline and to obtain pure acetanilide by purification of the collected crude acetanilide by crystallization. The recrystallizing solvent was chosen among ethanol, water and hexane. The acetanilide was synthesized and formed by acetylation of aniline and acetic anhydride, and it was then cooled to hasten the formation of crystals. After cooling, the mixture was filtered and dried to obtain the crude acetanilide. The crude acetanilide and the chosen recrystallizing solvent was mixed and heated in the water bath until the solid dissolved. The solution was filtered while hot and its filtrate was cooled in an ice bath. The filtrate was then filtered to collect the crystal residue formed. The crystals were washed with distilled water and allowed to dry to obtain the pure acetanilide. The weight of pure acetanilide was measured and the melting point of the pure acetanilide...
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...Department of Medical Technology Faculty of Pharmacy University of Santo Tomas, España, Manila Organic Chemistry Laboratory Recrystallization of Acetanilide Experiment 4 Author: Janina Erika G. Sese Group 8 – 2C Medical Technology (A.Y. 2015-2016) Members: Kathleen Danielle Marie A. Robles, Amiel C. Sabangan, Hanz Jefry A. Saliendra, Andrea Betina M. Vega, Anna Denise Z. Yang ------------------------------------------------- Date Submitted: October 28, 2015 ------------------------------------------------- ABSTRACT Recrystallization is the simplest and most widely used operation for purifying organic solids that differ in their solubility at different temperatures. In this experiment, three test tubes with water, hexane and, ethanol, respectively, were used to dissolve pure acetanilide. These test tubes were placed in a water bath for one to five minutes, then, were cooled through running water for the selection of the best solvent to use in recrystallization. Crude acetanilide was obtained by mixing two milliliters aniline and 20 milliliters distilled water with three milliliters acetic anhydride, which was cooled with running water. It was then filtered and dried for the procurement of crude acetanilide. This was mixed with 20 milliliters of the chosen solvent and heated through water bath until the solid was dissolved. Next, it was immediately filtered while hot. The filtrate was collected and was cooled with running water leading to...
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...Solubility is the property of a solid, liquid, or gaseous chemical substance called solute to dissolve in a solid, liquid, or gaseous solvent to form a solution of the solute in the solvent Solubility is defined as the ability of one substance to dissolve within another substance. What Affects Solubility? One of the factors that has a profound impact on solubility is temperature. Temperature, a measure of the available thermal energy, can increase the solubility of solids in liquids. This phenomenon can be observed in the creation of supersaturated solutions, or mixtures that contain far more of the solid dissolved in a liquid than would be possible under room temperature conditions. One application of supersaturated solutions can be seen in the production of rock candy where high-temperature sugar solutions readily form sugar crystals on the surface of objects placed in the solution. For gases that are dissolved in liquids, however, the trend is just the opposite. Cooler temperatures increase the solubility of gases in liquids, and higher temperatures decrease the solubility of gases. An example of the effect of temperature on dissolved gases can be found in the loss of dissolved oxygen in lakes or streams during extremely hot weather, a condition that results in the death of fish. In physical chemistry, saturation is the point at which a solution of a substance can dissolve no more of that substance and additional amounts of it will appear as a separate phase (as a...
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...Department of Chemistry PHYSICAL CHEMISTRY LABORATORY I Liquid-Liquid Equilibrium in a Ternary System #03 Anas Ahmed Al-Aidaros 200935483 Sec. 01 Instructor: Dr. Joanna Pajak Introduction: Objective Determination of the solubility limits in a ternary system of water and two other liquids, one of which is completely miscible and the other is partly miscible with water. According to the phase rule of Gibbs the variance F (number of degrees of freedom) of a system at equilibrium is equal to the number of components c minus the number of phases p plus 2, provided that the equilibrium is influenced only by temperature, pressure, and concentration. A system with three independent components has F=5-P degrees of freedom. An invariant point in a ternary system therefore contains five different phases in equilibrium with each other. An invariant point can for example consist of a vapor phase, a liquid phase, and three solid phases in equilibrium with each other. A ternary system with three phases (solid-liquid-vapor) in equilibrium with each other has two degrees of freedom. If the temperature is fixed, one degree of freedom remains. A phase diagram isotherm showing a ternary system with a vapor phase and a liquid phase requires therefore a line to mark the concentration range in which a solid phase is in equilibrium with the other two phases. A point needed to mark concentrations where two solid phases are in equilibrium with liquid and vapor. Experimental: Chemical...
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...Identification and Synthesis of an Unknown Ionic Compound 3/24/16 Department of College of Natural Science, Michigan State University, Farm Lane, East Lansing, MI 48825 Chemistry 161, Section 10 Dr. Joseph Ward Abstract The goal of this experiment is to identify an unknown compound. To identify this compound a series of test were performed to find the chemical and physical properties of the unknown compound. The test performed; flame test, solubility test, halide test, acetate test, ammonium test, nitrate test, sulfur test, carbonate test, calcium test and pH test. When the flame test of the unknown resulted in a brick red color, it was determined that the unknown contained calcium. Another calcium test was tested and proved that the unknown was calcium. Since the unknown is dissolvable in water, CaCO3 was no longer a possible candidate because it is insoluble. The pH test for the unknown was 5 whereas the pH for calcium chloride is 8 and the unknown tested negative for halide, therefor calcium chloride was not an option for the unknown as well. The last calcium compound left was calcium nitrate which also had a pH of 5 and a brick red flame test color. Introduction There was an unidentified white compound found in the lab. The goal of the experiment was to identify what the unknown compound is and how to dispose of it safely. In order to find this information, the compounds chemical and physical properties needed to be determined. This was a given...
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...Chemistry laboratory Pr. Zineb EDFOUF 3- Compound types CH 1213 Chemistry I Name: …………………………. Group: ….......................... Purpose: To examine the difference between ionic and covalent compounds and understand how their properties give rise to this categorization Introduction: It is amazing what early chemists accomplished even without an understanding of atomic make-up. Reading old chemistry textbooks shows how they justified some of their conclusions, which, with a few exceptions, were right on target. Some discussed the octet rule in terms of “valencies”, and they have it exactly right. What is interesting about this is that at that time they talked about this new sub-atomic particle that they were tentatively calling the “electron”. Another thing they had correct was the categorization of compounds into “covalent” and “ionic”. In class, you have discussed these compounds in terms of electrons, wherein ionic compounds transfer electrons and covalent compounds share electrons. How did the early chemists classify compounds, though, when they did not know what electrons were? They used properties, such as solubilities, melting points, and conduction. Solubility helps us to classify compounds as polar or non-polar, because, as a general rule, polar solutes dissolve in polar solvents (like water), while non-polar solutes dissolve in non-polar solvents (like oils). Conductivity means whether or not a compound will conduct electricity when it is dissolved...
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...“The Project” An Unknown Ionic Compound in the Landfill Introduction Upon discovery of an unknown solid ionic compound in a landfill by the Chemistry 1146 laboratory group, precautions were immediately taken and rigorous experimentations were begun to determine the identity of the compound. Determining the identity of this compound was very crucial for the safety of the community. The chemical and physical properties of the compound could then be identified and environmental hazards addressed. Questions that needed to be answered in relation to this unknown compound included: Is it a risk to people living nearby? What if it gets in the water supply? Does it contaminate the air? Is it reactive? Over a three week time-span the chemists experimented with the unknown compound to report the findings back to the community. After the unknown compound was identified, the chemists studied its properties and confirmed the identity by synthesizing the compound in the lab and comparing it to the unknown. Experimental Week 1 After a sample of the unknown compound (#21) was retrieved, various experiments were carried out to determine the chemical formula. An anion analysis was first performed on the unknown compound. A solution of the unknown compound was prepared by taking a small amount of the solid on the end of a scoopula and dissolving it in 2 mL of distilled water (DI water) in a test tube. The compound was then tested for the sulfate ion by placing 1 mL of the solution in a test...
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...inorganic nitrate salt is potassium nitrate. Nitrates are mainly produced for use as fertilizers in agriculture because of their high solubility and biodegradability. The main nitrates are ammonium, sodium, potassium, and calcium salts. Nitrates found in soil play an important role to the growth of plants and of the nitrogen cycle. In the soil, there are various bacteria, such a nitro fixing and denitrifying bacteria which are also important. The amount of nitrate found in soil varies. It depends on the location of the soil and the soil type. In this experiment, five samples of soils form different locations from the University of Guyana were used for testing. These areas were the Natural Science building area (Soil Sample 1), the Library (Soil Sample 2), behind area of Library (Soil Sample 3), and Health Sciences area (Soil Sample 4). D Phenylalanine, along with 2-3 drops of H2SO4 was added to the respective diluted soil samples to determine the degree of Nitrate present, depending on the resulting blue colour. Soil sample 1 has the highest Nitrate content, (indicated in results as +++) the other samples resulted in the same amount of Nitrates present (indicated in results as ++). Reference * Wolfgang Laue, Michael Thiemann, Erich Scheibler, Karl Wilhelm Wiegand "Nitrates and Nitrites" in Ullmann's Encyclopedia of Industrial Chemistry, 2006, Wiley-VCH,...
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...compounds. It is a very efficient method of purification, and an important industrial technique still relevant in the chemical world. (Williamson and Masters, 2010). Figure 1: process of recrystallization A pure, crystalline organic substance has a well-defined crystal lattice, a three-dimensional array held by London forces. Most organic solids melt between the range of 22℃ and 250℃. An impure organic solid does not have a well-defined lattice and needs to undergo recrystallization, in order to remove the impurities and to allow a perfect crystal lattice to grow. The four important concepts in the process of recrystallization are solubility, saturation level, exclusion, and nucleation (Williamson and Masters, 2010). Recrystallization is a process where in the impure organic solid will be dissolved in a hot solvent (solubility). When the solution is...
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...Experiment 7: Lipid Extraction I. Abstract Lipids are biomolecules that are used primarily for structural components of the cell, signaling molecules and energy storage purposes. Lipids are naturally occurring esters of long chain fatty acids with both hydrophobic chains, which is insoluble to polar organic solvents and hydrophilic chains which is soluble to polar organic solvents. Because of this conformation, they can assume a wide range of complex structures including fused rings. Lipids can be isolated from cells through different techniques and their presence can be tested through different qualitative tests. The sample choice is egg yolk and was used as a source of lipids in the experiment. Liquid-liquid extraction, separation of the organic and aqueous layer was used to extract the supernatant or extract. Also, thin layer chromatography or TLC was used to separate the different lipid components by using the Rf values computed. The farther the distance traveled by the compound (higher Rf), the more nonpolar the component, while the smaller the distance traveled, the more polar the component (lower Rf). Lecithin and cholesterol was not able to travel the plate. After, the isolated lipid was subjected to qualitative tests such as Acrolein test, test for phosphates, Leibermann-Burchard test and test for unsaturation. Acrolein tests determine the presence of glycerin; the test for phosphate detects phosphate groups in the structure of the lipid, Leibermann-Burchard uses cholesterol...
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...Symbols and Charges for Polyatomic Ions Formula Name Formula NO3nitrate ClO4NO2 nitrite ClO3CrO42chromate ClO22Cr2O7 dichromate ClOCN cyanide IO4MnO4 permanganate IO3OH hydroxide IOO22peroxide BrO3NH2 amide BrO2CO3 carbonate HCO32SO4 sulfate HSO42SO3Chemistry I sulfite HSO32C2OPolyatomic Ions oxalate HC2O44 3PO4 phosphate HPO423acids: PO3Here’s a list of common polyatomic ions andH2PO4phosphite 2Name S2OIon + thiosulfate HS3 NH Ammonium* AsO43- 4 arsenate BO33NO3 Nitrate 2SeONO selenate B4O724 Nitrite 2 2SiOOHsilicate SiF623 Hydroxide* 2C4HCN-6 tartrate 4O Cyanide Name perchlorate chlorate chlorite hypochlorite periodate iodate hypoiodite bromate hypobromite hydrogen carbonate (bicarbonate) hydrogen sulfate (bisulfate) hydrogen sulfite (bisulfite) hydrogen oxalate (bioxalate) hydrogen phosphate dihydrogen phosphate Acid Formula Acid hydrogen sulfide Name borate HNO3 Nitric Acid tetraborate HNO2 Nitrous Acid hexafluorosilicate (not really an acid) HOH Water HCN Hydrocyanic Acid SCNThiocyanate HSCN Thiocyanic Acid C2HClO2-acetate (an write ) Perchlorate* alternate way to HClO4 acetate is CH3COOPerchloric Acid 3O 4 ClO3 Chlorate* HClO3 Chloric Acid ClO2 Chlorite* HClO2 Chlorous Acid There are only two positive polyatomic ions: ClOHypochlorite* HClO Hypochlorous Acid + H O2 C2is3calledI the ammonium ion and Acetate HC2 H3 O2 Acetic Acid NH4Chemistry MnO4 Permanganate HMnO4 Permanganic Acid 2+ Hg2 Polyatomic Ions mercury(I) ion is called the SO4 2Sulfate* H2 SO4 Sulfuric Acid 2Sulfite*...
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...Lab Report Marco Huerta Partner: Sami Mrestani Chem 12B – Organic Chemistry 11/07/11 Lazik Benzocaine Objective: To prepare a local anesthetic, Benzocaine, by the direct estherification of p-aminobenzoic acid with ethanol. Abstract: Over the years many new local anesthetics have been synthesized and tested. Though many have not come into general use, the search for the perfect local anesthetic is still under way. An interesting fact about these compounds is that they all share common feature (see general structure below). At one end of the molecule is an aromatic ring. At the other is a secondary or tertiary amine. These two ends are separated by a central chain of atoms usually one to four units long. The aromatic part is typically and ester of an aromatic acid which is important to the bodily detoxification of these compounds. In our experiment, we created a topical anesthetic, Benzocaine, by the direct estherification of p-aminobenzoic acid. This was accomplished by reaction with absolute ethanol catalyzed by concentrated sulfuric acid and later neutralized with a 10% sodium carbonate solution. Neutralization raised the pH of the overall reaction system to about 8 creating a precipitate of Benzocaine. Recrystallization of the crude product was performed to increase purity. Our...
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...Introduction: Several methods have been developed over time in order to purify various organic compounds. One of the most basic and effective techniques known is recrystallization. Despite its decreased practice, recrystallization still remains one of the top methods in obtaining scalable amounts of ultra-pure organic materials. This technique essentially relies on the different solubility’s of compounds to be purified in a solvent. The impure material will thus dissolve in a hot solvent, allowing the removal of these impurities through filtration, which will then allow the desired compound to crystallize as it cools. Solvents and solubles are important factors in recrystallization; the substance should have a high solubility at elevated temperatures, and low solubility at low temperatures. Additionally, the solvent should have the capability of dissolving or not dissolving impurities, which will determine the occurrence of filtration. Compared to insoluble impurities, which are filtered once the compound dissolves in the hot solvent, soluble impurities are filtered out in solution as the compound is left behind. In some cases, decolorizing carbon may also be used to remove colored impurities. Also, it is important to effectively use the perfect amount of hot solvent to avoid dissolving much of the desired compound, which allows it to pass through the filter alongside the impurities. This solution is known as the mother liquor; the liquid that remains after filtration, containing...
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