Hydrolysis of benzamide

Experiment 18 Hydrolysis of benzamide Date: 18-5-2006 Objective To study the hydrolysis of benzamide into benzoic acid and to determine the melting point of the product. Introduction Benzamide reacts with an alkali and an acid to give benzoic acid under heating. The benzoic acid so formed is impure and is purified using a technique called recrystallization. This process involves the dissolving of the acid into boiling water to make a saturated solution and then allowing crystals to form. The crystals are then collected by suction filtration. Procedure . 3 g of benzamide was weighed out and put into a conical flask. 2. The benzamide was mixed with 50cm3 of NaOH. 3. The conical flask was fit with a cord and the mixture was heated for about 15 minutes. 4. The gas evolved was tested with a piece of pH paper. 5. The reaction mixture was cooled and hydrochloric acid was added until a white precipitate was formed. 6. The residue, then benzoic acid, was obtained by suction filtration. 7. The benzoic acid was dissolved with minimum amount of boiling water, and the solution was allowed to cool down to initiate the formation of the crystals. 8. The crystals were obtained by suction filtration and were dried in an oven for 1 night. 9. The dried crystals were weighed and its melting point range was determined. Data and Calculation . The gas evolved in step 4: NH3

  • Word count: 850
  • Level: AS and A Level
  • Subject: Science
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Preparation and analysis of a complex metal salt

Experiment 7 Preparation and analysis of a complex metal salt (15-12-2006) Objective . To prepare a sample of copper-ammonia complex salt. 2. To determine the ammonia content in the sample of salt. 3. To determine the metal content of the sample of salt. Results A. Determination of ammonium content HCl was added in excess into the complex salt. The NH3 ligands were protonated to NH4+ and were detached from the metal cation. The volume of HCl in excess was determined by titration using NaOH. The ammonium content of the salt was determined. * Weight of the complex salt used: (6.321 - 5.896) = 0.425g * Volume of HCl (0.6M) added onto the flask: 25cm3 No. of moles of HCl added: 25/1000 x 0.6 = 0.015 moles * The reaction of the titration is given by the following chemical equation: HCl + NaOH --> NaCl + H2O (1) Volume of NaOH (0.5M) used in the titration: 20.8 - 4.3 = 16.5 cm3 (2) No. of moles of NaOH used: 16.5 / 1000 x 0.5 = 8.25 x 10-3 moles (3) No. of moles of HCl in excess = No. of moles of NaOH used in titration = 8.25 x 10-3 moles * No. of moles of HCl reacting with NH3: 0.015 - 8.25 x10-3 = 6.75 x 10-3 mole * By the equation NH3 + HCl --> NH4Cl, Number of moles of NH3 in the sample of salt = no. of moles of HCl = 6.75 x 10-3 mole * Molar mass of NH3 : 14 + 1 x 3 = 17 g/mole * The mass of NH3 in the sample = 17 x 6.75 x 10-3 = 0.11475 g * % by mass

  • Word count: 1330
  • Level: AS and A Level
  • Subject: Science
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Extraction of Chlorine

Extraction of Chlorine The chlor-alkali electrolysis process is used in the manufacture of chlorine, hydrogen and sodium hydroxide solution. Of these three, the primary product is chlorine. In each one, a salt solution is electrolyzed by action of direct electric current that converts chloride ions to elemental chlorine [1]. Anode and cathode reactions in the membrane cell A membrane allows positive ions such as Na+ (aq), to pass through it, but not negative ions, like Cl- (aq), or water molecules. On one side circulating brine is in contact with a titanium anode and chloride ions are discharged producing chlorine gas [2]. (Figure 1) Figure 1: The membrane cell [3] Redox reactions involve electron transfer. Redox reactions can be split into two half-reactions, one producing electrons, and one accepting them [4]. If the ions in the electrolyte solution are positively charged, they will flow towards the cathode and be reduced. If the ions are negatively charged, they will flow to the anode and be oxidised. The extraction of chlorine is an example of such reaction: 2NaCl + 2H2O Cl2 + H2 + 2NaOH Anode: 2Cl- (aq) Cl2 (g) + 2e- Cathode: 2 H+ (aq) + 2e- H2 (g) Redox reactions in the membrane cell If chlorine is produced in the presence of sodium hydroxide solution it will combine with it to produce ClO- and Cl- ions,

  • Word count: 1467
  • Level: AS and A Level
  • Subject: Science
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Main Pollutants emitted by vehicle Engines

Main Pollutants emitted by vehicle Engines Main pollutants: How is it formed: Environmental problems: Hydrocarbons (HC) Formed when fuel is not fully burnt. Contributes to ground-level ozone when it reacts with NOX and sunlight. Cancer.i Respiratory problems. Carbon Monoxide (CO) Formed when substances containing carbon do not have access to enough air. Global warming.ii Ground ozone, which can damage plants and crops, and cause respiratory problems, even death. Nitrogen Oxide (NOX) Formed when fuels are burnt at high temperatures. Acid rain. Oxygen deficit. Haze air pollution.iii Contributes to formation of particles and smog. These can then cause health problems. Particles (PM10) Formed from the burning of fossil fuels. Can cause respiratory disease and premature death.iv Reduces visibility. Turns water in lakes and ponds acidic. Can damage crops.v There are three different types of vehicle engine: conventional, lean-burn and diesel. They all produce different types of exhaust emissions because of the ratio of air to fuel that they use. Conventional engines use high levels of fuel and so produce more nitrogen oxides. Lean-burn engines use high amounts of air and so produce more hydrocarbons. Diesel engines are like lean-burn engines, but produce high levels of particles and smoke.vi Acid rain NOX emissions are oxidised in the atmosphere to form

  • Word count: 1092
  • Level: AS and A Level
  • Subject: Science
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Winning a Metal from it's Ore

Title: Winning a Metal from its Ore Introduction: The initial purpose of the lab is to extract the most copper out of a given amount of malachite, the ore copper is found in. Metals are naturally found in rock called ore. To extract the metal from the ore two processes take place, smelting and roasting. Roasting is a process in which heat is used to decompose ions that are combined. The reaction for the roasting portion of this lab is. . Another method of extracting a metal from ore is smelting. The process of smelting uses heat and a reducing agent (in this case carbon) to extract the element itself. The reaction for the smelting process in this lab is. Hypothesis: Two initial hypotheses can be made. The first one is predicts the mass of CuO, shown in the work below. The predicted mass of CuO is 0.72g. The second hypothesis is the theoretical yield of copper from the second reaction. As demonstrated below - Materials and Equipment: (From Handout) .00g Cu2(OH)2CO3 copper(II) carbonate basic 0.50g C carbon black ring stand with ring clamp and clay triangle crucible and lid crucible tongs 2 weigh boats glass stir rod metal spatula gas burner and hose

  • Word count: 859
  • Level: AS and A Level
  • Subject: Science
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PPA1 Preparation of Potassium Trioxalatoferrate

Unit 1 PPA 1: Preparation of Potassium Trioxalatoferrate Aim: The aim of the investigation was to prepare Potassium Trioxalatoferrate (III) from Ammonium Sulphate and then calculate the percentage yield. Introduction a) Ligand The oxalate ion can act as a ligand as it binds to a central metal ion to form a complex ion by the donation of one or more electron pairs into unfilled metal orbitals. In this case three negatively charged oxalate ions surround one positively charged Fe3+. The three oxalate ions attach themselves to the Fe3+ at six points creating an octahedral shape. This results in the metal complex having a net total charge of -3. b) Potassium Trioxalatoferrate http://upload.wikimedia.org/wikipedia/commons/thumb/3/33/Potassium-ferrioxalate-2D.png/250px-Potassium-ferrioxalate-2D.png 07/03/10 c) Relevant Equations Step 1: (NH4)2Fe(SO4)2.6H2O + H2C2O4 --> FeC2O4 + H2SO4 + (NH4)HSO4 +6H20 Step 2: 6FeC2O4 + 3H2O2 + 6K2C2O4 --> 4K3[Fe(C2O4)3] + 2Fe(OH)3 Step 3: 2Fe(OH)3 + 3H2C2O4 +3K2C2O4 --> 2K3(Fe(C2O4)3) + 6H2O Percentage Yield Calculation (NH4)2Fe(SO4)2.6H2O --> 2K3(Fe(C2O4)3) + 6H2O Molar ratio 1 : 1 Actual Yield 4.86g mol= 0.0128 mol -1 mol= 0.0128 mol -1 mass= 5.03g mass=6.28g

  • Word count: 788
  • Level: AS and A Level
  • Subject: Science
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Thermal Decomposition of Calcium Carbonate

Introduction Calcium Carbonate, CaCO3 decomposes with heat, to produce Calcium Oxide, CaO and Carbon Dioxide, CO2. CaCO3(s) CaO(s) + CO2(g) The object of this practical exercise is to determine the enthalpy change for this reaction by an indirect method based on Hess' Law. Results Table Experiment 1: Mass of CaCO3 and weighing bottle 3.47g Mass of empty weighing bottle .08g Mass of CaCO3 used 2.39g Temperature of acid initially 22oC Temperature of solution after mixing 24oC Temperature change during reaction 2oC Experiment 2: Mass of CaO and weighing bottle 2.58g Mass of empty weighing bottle .00g Mass of CaO used .58g Temperature of acid initially 22oC Temperature of solution after mixing 27oC Temperature change during reaction 5oC Calculating the Enthalpy Change Experiment 1: Calculating the H1 for the reaction between CaCO3 and HCl Using the formula: Density = Mass Volume , We can work out the mass of liquid (HCl) Mass = Density x volume = 2.0 x 0.05 = 0.1 grams Using the calculated mass, we can work out the total energy transfer using the formula: Energy Transfer = Mass of Liquid x specific heat capacity x change in temperature = 0.1 x 4.2 x (24-22) = - 0.84 J From the results table, we can see that the temperature increased from 22oC to 24oC, so we can deduce that

  • Word count: 1350
  • Level: AS and A Level
  • Subject: Science
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Aluminium and its Extraction

EXTRACTION OF ALUMINIUM Bauxite is an orange-red igneous rock, which occurs naturally in the lithosphere, from which Aluminium is extracted. It contains 30-54% alumina, Al2O3 and other impurities such as clay, Iron (III) Oxide (Fe2O3), Silica (SiO2), and Titania (TiO2). Australia was the top producer of bauxite in 2007, with almost one-third world share. The Bauxite has to be purified by a process known as The Bayer Process. The Bayer process is the main industrial method of refining bauxite to produce alumina. The Bauxite rocks are crushed to smaller rock sizes. Then the bauxite is digested by mixing it with a hot solution of sodium hydroxide, NaOH at 175oC. This only dissolves the oxides of aluminium and silicon, but not the other impurities. The solution is further purified by filtering out the solid impurities. Carbon dioxide gas is then bubbled through the solution, which creates a weak carbonic acid, neutralising the solution and causing the aluminium oxide to precipitate, but leaving the other silicon impurities. The remaining solution is filtered once again and boiled to remove the water. The resultant product is purified aluminium oxide. After the purified aluminium oxide has been produced, the aluminium can be separated by a process known as The Hall-Heroult method. The alumina is dissolved in molten cryolite (Na3AlF6). Then mixture is then heated to

  • Word count: 1615
  • Level: AS and A Level
  • Subject: Science
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Determination of Chemical Oxygen Demand (COD) of a Given Sample of Waste Water

BCH 2005 Principles of Environmental Chemistry Experiment 4 Determination of Chemical Oxygen Demand (COD) of a Given Sample of Waste Water * Introduction The chemical oxygen demand(COD) is commonly used to indirectly measure the amount of organic compounds in water. Most applications of COD determine the amount of organic pollutants found in surface water , making COD a useful measure of water quality. It is expressed in the unit of mgL-1. In this practical, COD of a given sample is measured by back titration of the FAS solution with the remaining dichromate ions after reflux. For details, the sample is refluxed in concentration sulphuric acid with excess potassium dichromate solution. After reflux, the remaining K2Cr2O7 is titrated with FAS to determine the amount of potassium dichromate solution remained. As we have known the original amount of potassium dichromate in advanced, we can find out the amount of dichromate reacted with the organic solvent during reflux. Hence, that is the COD. This method is suitable for a wide range of wastes where a large sample size is preferred. COD values of > 50 mg O2 l-1 can be determined using this method. * Objective To determine the COD of a given sample of wastewater * Procedure Please refer to the lab manual * Results ) Titration of standard K2Cr2O7 with FAS Trial 2 3 Initial volume of FAS (ml) 3.30

  • Word count: 1455
  • Level: AS and A Level
  • Subject: Science
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Titrations in Modern Industrial Laboratories

Quality Control for Pharmaceutical Products Producing pharmaceutical products ready for consumer is important because Quality assurance is the sum of all parameters concerning the preparation and control of a finished product. It is a wide term commonly used for the confirmation and validity of various ways and measurements adopted to obtain a high quality procedure for intended use with guaranteed performance. Biological quality control of pharmaceutical products becomes essential and to keep the risks of producing pharmaceutical products as minimum as possible as they are ultimately to be consumed by living organisms, in particular the humans. A standard solution is a solution whose concentration is known accurately. Its concentration is usually given in mol dm-3. When making up a standard solution it is important that the correct mass of substance is accurately measured. It is also important that all of this is successfully transferred to the volumetric flask used to make up the solution. Titrations are important to understand how acids and bases react with each other, ways to understand detection of experimental error, and to experimentally calculate or figure out what a chemical or substance consists of or the properties it can contain. Titrations are a key tool in industry laboratories and for educational purposes. The right technique and precision of an experiment,

  • Word count: 823
  • Level: AS and A Level
  • Subject: Science
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