Hydrolysis of an ester
A-Level Chemistry Coursework: Hydrolysis of an ester Ying-Jun Ng For the hydrolysis of methyl benzoate, care must be taken throughout the procedure as a number of dangerous substances are being used. During the procedure a labcoat, goggles, and gloves must be worn throughout. Specific safety instructions for chemicals or procedures are explained in the step that they are introduced. Observations, readings, and necessary safety precautions are discussed in the same order as the procedure was carried out in. . Safety: Methyl benzoate is harmful is inhaled or is it gets into contact with the skin or eyes or if swallowed. So it is necessary to carry out the entire procedure in a well-ventilated area and gloves and goggles must be worn. Sodium hydroxide is a caustic soda and so is not very dangerous however regular safety precautions (goggles, labcoats and gloves) and care is still carried out to prevent spillages. Ethanol is highly flammable and dangerous substance as it contains methanol. Therefore, it should not come into direct contact with any flame. It is harmful it swallowed, inhaled or comes into contact with skin. Observations: Methyl benzoate is originally a transparent liquid however the addition of the sodium hydroxide, ethanol and anti bumping granules turns the liquid cloudy. 2. Safety: As a Bunsen burner is being used a heat mat should be placed
Making Aspirin
In this task we were asked to synthesise aspirin from salicylic acid (2 - hydroxybenzoic acid) and ethanoic anhydride (CH3COOCOCH3) in a laboratory scale and prepare a pure silver chloride sample from the solutions of silver nitrate (AgNO3) and sodium chloride (NaCl) of known concentrations. Now I am going to describe the preparation of these two items and estimate the purity of one of my samples. Preparation of aspirin: Now I am going to explain the preparation of the aspirin; Materials : (a) ethanoic acid (b) ethanoic anhydride (c) salicylic acid (d) water cooled condenser (e) filter paper (f) Buchner funnel (g) vacuum oven (h) melting point recorder machine etc. Procedure ) Firstly we mixed 5 ml of ethanoic acid with 5 ml of ethanoic anhydride in a 50 ml round bottomed flask. 2) After that we added 5 g of 2- hydroxybenzoic acid and a few anti - bumping stones . 3) Then we attached a water cooled condenser and reflux the mixture for 30 minutes over a Bunsen and gauze. 4) Then we pour the mixture slowly into 100 ml of cold water which is being stirred vigorously. 5) After that we removed the 2 - ethanoyloxybenzoic acid by filtration through a Buchner funnel. 6) Then we removed the product from the fume cupboard and dried it in a vacuum oven at about 80 degree Celsius. 7) Then we weight the dried product and recorded its melting point. Chemical reaction:
An investigation into the efficiency of alcohols as fuels.
Joe Taylor 11T Chemistry coursework An investigation into the efficiency of alcohols as fuels Planning The aim of the experiment is to investigate the use of five alcohols as fuels. The combustion of alcohols is exothermic, meaning that when burnt they give off more heat than they take in. This makes them useful as fuels, and many countries are adopting alcohol fuels, for example Brazil. Therefore it seems useful and topical that the efficiency of the alcohols should be investigated. The alcohols methanol, ethanol, propan-1-ol and propan-2-ol will be tested. In order to evaluate the efficiency of these alcohols as fuels, their enthalpies will be investigated. Alcohols are perfect for testing, as they are all liquids with the same weight. Therefore weight is not a variable, and it is only the heat given off that is to need be considered. From previous organic chemistry studies the structures and formation of alkanes, alkenes and alcohols were known, along with the energy values for the bonds within alcohols themselves. This allowed for the creation of the bond energy table below. Bond Bond Energy (kJmol-1) C-H 435 O=O 497 C=O 803 H-O 464 C-C 347 C-O 358 These are the alcohol's formulae: Methanol: CH3OH Ethanol: C2H5OH Propan-1-ol: C3H7OH Propan-2-ol: C3H7OH Pentanol: C5H11OH Each of these reacts with Oxygen (0=0) in combustion For a pictorial
Super critical carbon dioxide - its characteristics and use in making decaffinated coffee.
Green Chemistry Super critical carbon dioxide By Gemma Taylor Part 1: When there is a relatively high temperature and pressure the line between whether a material is in its liquid or gas state begins to blur. The material has properties similar to a gas and a liquid. It is like a gas as it expands to fill any available space and it is like a liquid as it is able to be used as a solvent. When the materials are in this state they are called a superficial fluid. Carbon Dioxide forms a superficial fluid when there is a pressure of around 73 atmospheres and when the temperature is about 31 degrees. As this is a low critical temperature it makes critical carbon dioxide very easy to work with. Another useful feature of critical carbon dioxide is that when it is in its solvent form it is able to be altered by making slight adjustments to temperature and pressure. The phase diagram below of carbon dioxide shows us that its triple point ( where all states of carbon dioxide exist together) is found at the temperature -56.4 degrees and a pressure of 5.11 atm. The liquid state of carbon dioxide does not exist in the normal atmosphere pressure (1 atm). The solid carbon dioxide changes directly into its gaseous state. It is because of this property that solid carbon dioxide (also called dry ice) is a very useful refrigerant. At higher temperatures then the critical carbon dioxide state
Reactions of aldehydes and ketones. The purpose of this experiment is to compare some reactions of ethanal and propanone.
Date: 8/11/2011 Exp. No.: 25 Title: Reactions of aldehydes and ketones Aim: The purpose of this experiment is to compare some reactions of ethanal and propanone. Introduction: In this experiment, ethanal and propanone were chosen as they are relatively safe. The structures of the 2 compounds are as follow: Ethanal Propanone In this experiment, we are going to investigate the following reactions of these 2 compounds: . Addition 2. Condensation 3. Oxidation 4. Iodoform reaction Apparatus and chemicals: Apparatus: Safety spectacles, hot water bath, cold water bath, test tubes, beakers Chemicals: Saturated hydrosulphite solution , 2,4-dinitrophenylhydrazine solution, 0.1M potassium dichromate solution, 1M sulphuric acid, Fehling's reagent (Fehling solution A + Fehling solution B), 0.05M Silver nitrate solution, 2M sodium hydroxide solution, 2M ammonia solution, iodine solution 10% (in KI(aq)) Procedures: Part 1: Addition reaction with sodium hydrogensulphite . About 2 cm3 of saturated sodium hydrogensulphite solution was added into a test tube. 2. The test tube was put into a cold water bath. 3. Similar volume of ethanal was added drop by drop into the test tube. 4. The experiment was repeated using propanone instead of ethanal. Part 2: Condensation reaction with 2,3-dinitrophenylhydrazine . About 1 to 2 drops of ethanal was added
UV-Visible Spectrophotometry
Name: Chu Ka Ki Student No.: 50555542 Group: 1 Date: 17-02-2005 Experiment: 2 BCH 2004 Principle of Analytical Chemistry Lab Report (Report One) Title: UV-Visible Spectrophotometry Aim: To determine phosphate composition in cola beverages by UV-Visible spectrophotometry and pH titrimetry. Introduction: UV-Visible spectrophotometry is one of the most important methods for the chemical analyze. Ultraviolet-Visible spectroscopy or Ultraviolet-Visible spectrophotometry (UV/VIS) involves the spectroscopy of photons (spectrophotometry). It uses light in the visible and adjacent near ultraviolet (UV) and near infrared (NIR) ranges. In this region of energy space molecules undergo electronic transitions. The method is used in a quantitative way to determine concentrations of an absorbing species in solution, using the Beer-Lambert law: where A is the measured absorbance, I0 is the intensity of the incident light at a given wavelength, I is the transmitted intensity, L the length of the cell, and c the concentration of the absorbing species. For each species and wavelength, ? is a constant known as the extinction coefficient. The absorbance A and extinction ? are sometimes defined in terms of the natural logarithm instead of the base-10 logarithm. Methodology: Colorimetric Analysis: At the beginning, 4cm3 decarbonated cola was transferred into a 100cm3
Determination of a Rate Equation
Determination of a Rate Equation Introduction: The rate of reaction is the rate of depletion of reactants or the formation of a product during a chemical reaction. It is expressed by units of concentration over the time taken for the reaction to take place. (Avogrados, 2010) Aim: To plan and carry out an experiment involving a graphical method to determine how the concentration of each component affect the rate of reaction in this reaction: 2HCl + Na2S2O3 --> 2NaCl + SO2 + S + H2O Background Information: Sodium thiosulphate and hydrochloric acid are both clear colourless solutions. They react together according to this equation: 2HCl + Na2S2O3 --> 2NaCl + SO2 + S + H2O When these solutions are mixed together, a yellow precipitate, sulphur, is produced. This causes the mixture to appear cloudy. The faster the rate of the reaction, the faster the solution appears cloudy. There are four basic factors that affect the rate of a reaction namely: Temperature, concentration/ pressure (in gases), physical state/ surface area of the reactants and the presence or absence of a catalyst [(Think Quest, 2008) and (WebChem, 2005)] Basic Idea: * Two sets of experiments will be carried out. In each case, the concentration for a single reactant will be varied * All other factors should remain constant * Conical flask containing the mixed reactants will be placed on a paper
Analysis Of Commercial Vitamin C Tablets
Experiment 5 Date: 18-10-2005 Analysis Of Commercial Vitamin C Tablets Objective To determine the mass of Vitamin C in 1 pill of Vitamin C tablet. Introduction In this experiment, the concentration of sodium thiosulphate solution is not given. So, we need to standardize it through titration. Sodium thiosulphate reacts with iodine in the following reaction: I2 + 2S2O32- ----------------->2I- + S4O62- After an amount of S2O32- is added, the solution of I2 turns pale yellow. When starch solution is added and more S2O32- is added, the solution reaches its end point, which is colorless. In this way, the molarity of the thiosulphate solution is determined. Vitamin C could be oxidized by iodine in the presence of acid in the following equation: Due to the low solubility of iodine, direct titration of iodine solution and Vitamin C is unsuitable. Then how could the experiment be done? The experiment could be done by adding acidified Vitamin C solution into potassium iodide solution. Then, we add potassium iodate to allow the following reaction to take place: IO3- + 5I- + 6H+ ----------------> 3I2 + 3H2O I2 formed in this reaction could react with the Vitamin C in as mentioned in the above equation. The I2 not yet reacted would then be titrated against thiosulphate solution, like the first equation, to determine its amount. This method is a kind of back titration. It is
Investigation of Some of the Properties of a Pair of Cis-Trans Isomers
Experiment18 Aim To determination the partition coefficient of ethanoic acid between water and butan-2-ol. Procedure . The room temperature was recorded. 2. 15cm3 of the given aqueous ethanoic acid and 15cm3 of butan-2-ol were poured into a 100cm3 separating funnel, using suitable apparatus. The funnel was stoppered and was shook vigorously for 1 to 2 minutes. (The pressure in the funnel was released by occasionally opening the tap.) 3. 10cm3 of each layer was separated approximately. (The fraction near the junction of the two layers was discarded.) 4. 10.0cm3 of the aqueous layer was pipetted into a conical flask and was titrated with 0.1 M sodium hydroxide solution using phenolphthalein. 5. Using another pipette, 10.0 cm3 of the alcohol layer was delivered into a conical flask and was titrated with 0.1 M sodium hydroxide solution. 6. Steps (2) to (5) was repeated with another separating funnel using the following volume: 25cm3 of aqueous ethanoic acid and 15cm3 of butan-2-ol 7. For each experiment, the ratio of the concentration of ethanoic acid in the aqueous layer to that in the butan-2-ol layer was calculated. Result Room temperature: 29? Volume of butan-2-ol: 15 cm3 Volume of 0.2M ethanoic acid / cm3 Volume of 0.1M NaOH titre for aqueous layer / cm3 Volume of 0.1M NaOH titre for alcohol layer / cm3 Partition coefficient K= 5 0.00 2.55 0.796 25
