Experiment to determine the ethanol content of wine

Experiment to Determine Ethanol Content of Wine The purpose of this experiment is to determine the ethanol content of each of the wines and compare the value determined to the value quoted on the label. These results can then be used to conclude which region is more accurate in quoting the value of the ethanol content of the wine. This experiment takes advantage of the fact that ethanol is less dense than water in solution. The density of ethanol at 20°C is 0.789 g/cm3 while the density of water at the same temperature is 0.998 g/cm3. It then follows that different solutions of ethanol and water will have different densities also, because the relative volume of ethanol increases and water decreases so the density of higher percentage ethanol solutions will be less than the density of lower percentage ethanol solutions. This occurs because water molecules are much smaller than ethanol molecule, meaning more water molecules can "pack" into a smaller volume than ethanol molecules, meaning there is more mass per unit volume of water compared to ethanol, meaning it has a higher density. In this experiment, solutions of ethanol in water were made up, going from 0% to 20%. These were then weighed, and the density of the ethanol was calculated. From this, a graph of percentage ethanol solution against density was made. This graphs later compared to the density of the wine, so

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Preparation of propanone from propan-2-ol

Date: 11/10/2011 Exp. No.: 23 Title: Preparation of propanone from propan-2-ol Aim: The aim of this experiment is to prepare propanone by oxidizing propan-2-ol with acidified potassium dichromate solution. Introduction: Ketones and aldehydes are important series in preparation of other compounds and they are commonly prepared by oxidizing alcohol which is done in this experiment. The experiment is an oxidation reaction where a secondary alcohol (propan-2-ol) is oxidized by acidified potassium dichromate. The reaction does not need to be heated but should be placed in an iced water bath as the reaction is highly exothermic. The product is propanone and no catalyst is needed for the reaction. The propanone is serparated from the reaction mixture by simple distillation and is purified using anhydrous cacium chloride. The equation of this reaction is as follow: Chromic acid is produced in situ by adding potassium dichromate (VI) with sulphuric acid and water. K2Cr2O7 + H2O + 2H2SO4 ? 2 H2CrO4 + 2 NaHSO4 The term chromic acid is usually used for a mixture made by adding concentrated sulfuric acid to a dichromate, which may contain a variety of compounds, including solid chromium trioxide. Chromic acid features chromium in an oxidation state of +6. It is a strong and corrosive oxidising agent. Apparatus and chemicals: Apparatus: Quick-fit distillation setup,

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Write an essay on electrode potentials.

F7 Essay Writing (Electrode Potentials) Q. Write an essay on electrode potentials. Outlines: (I) What are electrode potentials? (a) associated with equilibria of redox systems (half cells): e.g. metal / metal ion system ; non-metal / ion system ; ion / ion system; (b) reactivity, tendency for reduction to occur (losing electrons) and potential difference; (c) the potential difference of a half cell cannot be measured alone, but a relative value could be measured with another reference half cell / reference electrode; (d) a standard hydrogen electrode [SHE] (in which the emf is defined as zero) is used as the reference electrode; (II) How are electrode potentials measured? (a) concentration, temperature and pressure affect the emf of SHE, and the standard electrode potentials are obtained under conditions of 298K, 1 atm and conc. of 1M. (b) set up a cell with SHE and a salt bridge of electrolyte (e.g. KNO3); (c) a potentiometer is used to measure the cell emf (maximum potential difference), and the sign of cell emf = polarity of the right hand electrode. (III) How are electrode potentials used? / Application of electrode potentials? (a) calculation of cell emf ; (b) prediction of reaction feasibility and limitations. ~ Sample Essay ~ An electrode potential is the difference in an potential between an electrode and its surrounding electrolyte. It is

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Experiment to Determine Acidities of Wine. The purpose of this experiment is to determine the total and volatile acidities of each of the wines and compare them.

Experiment to Determine Acidities of Wine The purpose of this experiment is to determine the total and volatile acidities of each of the wines and compare them. Acidity is a major contributor to the taste of wines. This is especially important in white wines, because there are very little tannins found in it, so acidity can affect the taste of the wine much more than in red wines. In this experiment, 0.1M Sodium Hydroxide solution is needed for titrations. Because this is not a standard solution, it is first standardised using oxalic acid. In order to calculate the total acidity of the wine, a titration with 0.1M sodium hydroxide is carried out with a pH meter. The pH of the wine and sodium hydroxide solution is measured when a certain volume of NaOH is added each time, and a titration curve of volume against pH is plotted. The volume for the solution to reach a pH of 8.2 is recorded. This is because NaOH is a strong alkali and wine is a weak acid, so the pH lies more to the side of the alkali. A pH of 8.2 as the equivalence point is a value agreed on by winemakers. In order to calculate the total acidity of the wine, a representative acid must be used. This must be chosen because wine contains multiple different acids, which require different moles of NaOH to neutralise them. Tartaric acid was chosen as the representative acid for the wine, because it is thought to

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Revision Notes. Substances Manufactured for use in Industries. Chemicals, alloys and polymers.

.1 Manufacture of Sulphuric Acid Uses of Sulphuric Acid Sulphuric Acid, H2SO4, has many uses in our daily life. A few examples are: (a) Manufacture of fertilisers such as ammonium sulphate, (NH4) 2SO4 (b) Manufacture of electrolyte in lead-acid accumulators (c) Manufacture of soaps and detergents (d) Manufacture of pesticides (insecticide) (e) Manufacture of plastic items such as rayon and nylon (f) Manufacture of paints Manufacture of Sulphuric Acid in industry . Sulphuric acid, H2SO4, is manufactured in industry through the Contact Process. 2. The manufacturing of sulphuric acid, H2SO4, in industry involves three stages. Stage Aim Stage 1 Sulphur dioxide, SO2, gas can be produced by burning sulphur in air. S + O2 SO2 To produce sulphur dioxide, SO2, gas Stage 2 The gas mixture of sulphur dioxide and oxygen is passed over vanadium(V) oxide, V2O5 (catalyst) at a temperature of 450-500 ºC and under pressure of 1 atmosphere. 2SO2 + O2 2SO3 To produce sulphur trioxide, SO3 gas Stage 3 Sulphur trioxide, SO3, gas is dissolved in concentrated sulphuric acid, H2SO4 to form oleum, H2S2O7. SO3 + H2SO4 H2S2O7 Water is then added to the oleum, H2S2O7 to dilute it to produce sulphuric acid, H2SO4. H2S2O7 + H2O 2H2SO4 To produce sulphuric acid, H2SO4 The three stages involved in the Contact process Environmental

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Experiment investigating hydrogen bonding in different chemicals.

Tsuen Wan Public Ho Chuen Yiu Memorial College Form 6 Chemistry Practical Experiment 8: Hydrogen Bonding Date of experiment: 27-1-2011 Objective: A. To discover the existence of hydrogen bonds between ethanol molecules B. To measure the strength of hydrogen bond formed between ethanol molecules C. To investigate the formation of hydrogen bonds between molecules of ethyl ethanoate and trichloromethane D. To measure the strength of hydrogen bonds formed between molecules of ethyl ethanoate and trichloromethane Introduction: A hydrogen bond is the attractive interaction of a hydrogen atom with an electronegative atom, such as nitrogen, oxygen or fluorine, that comes from another molecule or chemical group. The hydrogen must be covalently bonded to another electronegative atom to create the bond. These bonds can occur between molecules, or within different parts of a single molecule. The hydrogen bond (5 to 30 kJ/mol) is stronger than a van der Waals interaction, but weaker than covalent or ionic bonds. This type of bond occurs in both inorganic molecules such as water and organic molecules such as DNA. Intermolecular hydrogen bonding is responsible for the high boiling point of water (100 °C) compared to the other group 16 hydrides that have no hydrogen bonds. Intramolecular hydrogen bonding is partly responsible for the secondary, tertiary, and quaternary structures

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Investigation to determine the Relative atomic mass of Li

Investigation to determine the Relative atomic mass of Li Results and calculations for the first method. Mass of Li used : 0.12g Start volume of Water : 55.5ml Final volume of water : 250.0ml Volume of hydrogen produced : 194.5ml Now based on these results I t is possible to calculate the concentration of the limewater. Calculate the number of moles of hydrogen produced: We have 195ml of hydrogen that has been produced. - This is equal to 0.195 dm3 Since 24dm3 is one mole of hydrogen at room temperature. - 0.195 dm3 = 0.008125 mol Calculate the number of moles of Li reacted: Using the equation: 2Li (s) + 2H2O (l) --> H2 (g) + 2LiOH (aq) 2 : 1 One can see the reacting ratio is 2:1, the no. moles of Li will be twice that of H2. - Moles of Li = 2 x 0.008125 mol - Moles of Li = 0.01625 mol Calculate the relative atomic mass of Li: As the mass of Li and No of moles used are know, it is possible to calculate the relative atomic mass of Li. - Mass of Li = 0.12g - No Moles of Li = 0.01625 mol - Relative atomic mass = mass/no moles - 0.12/0.01625 = 7.3846 - Relative atomic mass of Li = 7.38 Results and calculations for the second titration method. 2 3 End Burette vol (ml) 46.70 43.95 43.70 Start Burette vol (ml) 06.50 01.65 01.30 Amount used (ml) 40.20 42.30 42.40 Using the two best titres (within 0.1 ml),

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Design two experiments, one using titration and one using gas collection to show that H2SO4 is a dibasic acid.

Chemistry Practical Write-Up Aim: Design two experiments, one using titration and one using gas collection to show that H2SO4 is a dibasic acid. Gas Collection Experiment Prediction: If H2SO4 is dibasic it should give off a volume of hydrogen molecules, equal to the volume of H2SO4 used, below I have calculated how much gas to expect: H2SO4 + Mg › MgSO4 + H2 H2SO4 Concentration: 1 Mol/dm3 Volume: 0.025dm3 Moles: 1x0.025 = 0.025 H2 Moles: 0.025 0.025 * 24 Volume: 0.6dm3 Apparatus: Conical Flask, Magnesium, H2SO4, Bung, delivery tube, bowl of water, measuring cylinder. Diagram: Method: * Setup Apparatus as shown in the diagram. * Fill a conical flash with 25cm3 H2SO4. * Fill the measuring cylinder with water, making sure there are no bubbles, and turn it upside down in the water bath. * Drop the magnesium into the conical flask, and place the quickly place the bung on top. * The hydrogen gas will begin to displace the water in the measuring cylinder, wait until this stops, and record the results in a table like shown below, repeat until you have 3 results and calculate the average amount of gas evolved. Gas(dm3) - 1 Gas(dm3) - 2 Gas(dm³) - 3 Gas Average(dm³) To keep the results accurate we will keep all equipment and solutions used the same every time, we will do this experiment 3 times and take the average of the readings, and use this to see if

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Chiral Drugs What is chirality? Chirality is the property possessed by a molecule with such spatial arrangement of atoms that it cannot superimpose on its mirror image.

Chiral Drugs What is chirality? "Chirality" is the property possessed by a molecule with such spatial arrangement of atoms that it cannot superimpose on its mirror image. The object and mirror- image pair of molecules has the same constituents and structural formula. Their relationship with each other is similar to our left and right hands. The carbon atom of a simple chiral centre has four different groups arranged tetrahedrally (Fig. 1). Isomers of such nature are called enantiomers. Fig.1: A chiral molecule with tetrahedral arrangement and its mirror image. There are three types of stereoisomers, namely enantiomers, diastereomers and geometrical isomers. . Enantiomers are two stereoisomers containing asymmetric carbon atoms related as non-superimposable object and mirror images. If an enantiomer rotates polarized light to the right or in a clockwise direction, it is said to be the (+) or the dextrorotatory isomer. On the other hand, if the plane polarized light is rotated to the left or in a counter-clockwise direction, the isomer is called as the (-) or the levorotatory isomer. Enantiomers are identical in chemical and physical properties except for the direction of rotation of plane polarized light. 2. Diastereomers are stereoisomers that are not related as object and mirror images. They contain at least two asymmetric carbon atoms. Unlike enantiomers, the

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The Synthesis Of Phenacetin From p-Acetamidophenol

CH1751B - EXPERIMENT 15 The Synthesis Of Phenacetin From p-Acetamidophenol Introduction: "Phenacetin is an analgetic and an antipyretic reagent which acts in the body by temporaririly inhibiting prostaglandin synthesis in the central nervous system". Aim: * To synthesise Phenacetin from p-Acetamidophenol and purify it by recrystallisation. * Analyse purity of Phenacetin produced, by comparing the melting point with the literature values, the appearance and the Infrared Spectrum. Method: Sodium metal (0.6g, cut into small pieces) was cautiously placed into a dry 100cm3 round flask by taking the flask to the "sodium" balance and placing the sodium directly into the flask. A dry reflux condenser was attached and industrial methylated spirits (IMS, 15cm3) was added. A vigorous reaction occurred for 5-10 minutes under reflux until most of the sodium had dissolved. Once the solution had cooled 3.8g of p-acetamidophenol was added. Through the top of the condenser ethyl iodide (3.0cm3) was introduced to the pale green mixture and the mixture boiled at reflux temperature (20-25°). Ethyl iodide was obtained from a burette in the fume hood few minutes before its use, due to its flammable nature and harmful vapour. A darkening green colouration occurred while p-acetanilide dissolved changing through to brown and then yellow. Once the reflux was completed 40cm3 of water was

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