risks of electricity
WHAT ARE THE RISKS FROM ELECTRICITY? Harm can be caused to any person when they are exposed to 'live parts' that are either touched directly or indirectly by means of some conducting object or material. Voltages over 50 volts AC or 120 volts DC are considered hazardous. Electricity can kill. Each year about 1000 accidents at work involving electric shocks or burns are reported to the Health and Safety Executive (HSE). Around 30 of these are fatal, most of them arising from contact with overhead or underground power cables. WHO IS MOST AT RISK FROM ELECTRICITY? Anyone can be exposed to the dangers of electricity while at work and everyone should be made aware of the dangers. Most electrical accidents occur because individuals: * are working on or near equipment which is thought to be dead but which is, in fact, live * misuse equipment or use electrical equipment which they know to be faulty. LEGAL DUTIES AND OBLIGATIONS AROUND ELECTRICITY As well as a moral duty on employers to protect employees and members of the public, General Health and Safety Legislation covers all employers and workplaces. In addition, specific duties and obligations are laid out in the following regulations: These regulations apply to all aspects of the use of electricity within the workplace from electrical supplies to the use of electrical equipment. They place a duty on employers,
Preperation of Antifebrin
Preparation of Antifebrin In this experiment, I am going to prepare the organic compound of antifebrin from readily available chemical reagents. Antifebrin is an odourless solid chemical of white flake-like appearance. Chemically, antifebrin is the amide phenylethanamide CH3ONHC6H5. It's slightly soluble in water. It does have the ability to self-ignite if it reaches the temperatures of 545°c but otherwise it's a stable compound. The pure crystals of antifebrin are plate shaped and white in colour. The antifebrin in this experiment is prepared from the reaction between phenylammonium chloride (C6H5NH3Cl) and ethanoic anhydride[ (CH3CO)2O ]. Chemical Equation for the Reaction: C6H5NH3+ Cl- + (CH3CO)2O CH3ONHC6H5 + CH3OOH + HCl Procedure & Observations: Procedure Observation Dissolve 1.0g of phenylammonium chloride in 30cm3 of water in a conical flask. Phenylammonium chloride is a greyish-green crystal like product. Adding water to it gives a solution pale grey with green tinge. After dissolving the solutions turns clear with a green-grey colour and no precipitate. Prepare a solution of 6.0g of sodium ethanoate in 25cm3 of water in a conical flask. Sodium ethanoate is a white powder. It dissolves completely in water to give a colourless solution. Carefully add 2cm3 of ethanoic anhydride to the solution of phenylammonium
Production of Ethanol - Fermentation Vs Hydration
Production of Ethanol Fermentation Vs Hydration Ethanol, C2H5OH, is an alcohol produced industrially with many uses. Some of these include being used largely in the production of alcoholic beverages, cosmetics, antiseptics, drugs, inks, detergents and in solvents, and more over, it is very essential when mixed with petrol to make a bio-fuel, when made using renewable sources via fermentation. Ethanol can be produced by a number of ways, and in industry, it is made by the hydration of crude oil, or the fermentation of sugar. In the Hydration method, Crude oil, in this case - Ethene, as a natural gas - is essentially hydrated, meaning, water is added and Ethanol is the product of this reaction. Ethene, C2H4, is produced when crude oil is cracked, after being collected through the fractional distillation of fossil fuels that have been burnt. Water, H2O, is then reacted with the Ethene under a high temperature (approx 300oC) and a high pressure (60atm). Below is an equation of this reaction: CH2=CH2 (g) + H2O (g) › C2H5OH (l) As you can see, there is a double bond between the two molecules of CH2 in the Ethene. When Hydration occurs, the water added converts this double bond to Ethanol, which is the only product of this reaction. Fermentation, on the other hand, is the production of Ethanol by the use of plants. During this reaction, Carbohydrates from plants, mainly
dDetermination of the partition coefficient of ethanoic acid between water and butan-2-ol.
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
Redox titration
Date: 3rd December, 2010 Name: Merish Farooq Experiment no.3 Title: A redox Titration between Manganate (VII) and Iron (II) Objective: To determine the x in the formula Fe (NH4)2(SO4)2•xH2O by titration against a standard solution of potassium manganate (VII) (permanganate). Theory: The experiment involves a redox reaction between potassium manganate (VII) and ammonium Potassium manganate (VII) is used in the experiment as it reacts completely and it is its own indicator. Potassium manganate (VII) solution is a strong oxidizing agent. In an acidic medium, manganate(VII) ion undergoes reduction as shown below. MnO4- (aq) + 8H+ (aq) + 5e- --> 4H2O (l) + Mn2+ (aq) Ammonium Iron (II) sulphate is a strong reducing agent because of the presence of Iron (II) ions. Iron (II) ions can be oxidized to form Fe3+ which is yellow in color. Manganate (VII) ions are purple in color, when the MnO4- are reduced to Mn 2+, the color of the solution becomes pale pink, thus a self indicating titration can occur According to the overall reaction: MnO4- (aq) + 5Fe 2+ (aq) +8H+(aq) --> Mn2+(aq) +5Fe3+(aq)+4H2O(l) Between the titration of potassium manganate (VII) solution and ammonium iron (II) sulphate solution, The molarity of ammonium iron (II) Apparatus: Safety spectacles 25cm3 pipette Pipette filler 4 conical flasks 50cm3 burette Small funnel White tile Wash-bottle
History of table of Elements
Periodic Table of Elements The periodic table of elements or less commonly know as Mendeleev's table is a chart of all the chemical elements. This important discovery was credited to a Russian chemist named Dmitri Mendeleev. It was discovered when Dmitri was trying to teach his class a way to learn the elements faster and easier. He wrote down the name of the element as well as the atomic number and atomic weight on pieces of paper. He laid all the known elements down on a table and looked for similarities among them. He put them from lowest atomic mass to the highest. Once he had them in order he noticed that some elements were missing. From the information he had gained he could figure out the unknown elements masses. He then could figure out the atomic masses of the unknown elements by averaging the atomic masses of the elements above and below the unknown element. From the table he had just made he could figure out the atomic mass, melting point, density, appearance, formula of chloride, and formula of oxide of the missing elements. Astonishingly his predictions were later found true. Before Dmitri Mendeleev, a French noble prominent named Antoine-Laurent de Lavoisier had made a similar type of table. In 1789 he had grouped 33 elements into gases, metals, non-metals, and earths. Although this was a great leap in chemistry it wasn't the best. Over the years chemists
Electrochemistry Experiment. Objective: To investigate the effect of change in lead(II) ion concentration on the potential of the Pb2+(aq) ∣Pb(s) electrode
Tsuen Wan Public Ho Chuen Yiu Memorial College Form 6 Chemistry Practical Experiment 15: Electrochemistry Date of experiment: 8/4/2011 Introduction: Redox reactions are reactions where the oxidation states of the atoms change. The atoms are either oxidized or reduced, depending if they lose or gain electrons. Electrochemical cells are devices that cause a current from redox reactions. It is set up so that electrons lost from one of the reagents can travel to another reagent. This creates a voltage, which is also known as the electric potential difference. This voltage can be read if a high-resistance voltmeter or multimeter is connected to the circuit Salt bridge is used to allow migration of ions between two electric cells to maintain neutrality of solutions. It is usually made up of a filter paper moistened with an inert solution or an inert solution/gelatine salt bridge to prevent oxidation of certain ions. This experiment is divided into 2 parts: part A and part B. Part A Objective: To investigate the effect of change in lead(II) ion concentration on the potential of the Pb2+(aq) |Pb(s) electrode Introduction: This experiment investigates the e.m.f. of the cell: Cu(s) |Cu2+(aq) |Pb2+(aq)|Pb(s) Keeping the ion concentration in the copper electrode system constant(1M) and varying the ion concentration in the lead electrode system, the effect of change in
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
Revision notes - Test For Gases and Ions
Tests for Gases Name Formula Test Observations Hydrogen H2 Ignite gas. Squeaky pop is heard. Oxygen O2 Place a glowing splint in a sample of the gas. The glowing splint relights. Carbon dioxide CO2 Bubble gas through limewater (saturated solution of calcium hydroxide) A solution turns from colourless to cloudy. A white (milky) precipitate of calcium carbonate forms which is sparingly soluble. Ammonia NH3 Test for gas using damp red litmus paper. Litmus paper turns blue. Chlorine Cl2 Test 1 Test for gas using damp litmus paper (red or blue) Chlorine bleaches the litmus paper very quickly. Test 2 Test for gas using moist starch-iodide paper. The paper turns blue-black. Test 3 Pass gas through a solution of a bromide. The solution turns from colourless to orange. Test 4 Pass gas through a solution of an iodide. The solution turns from colourless to brown (possibly with a black precipitate, iodine). Nitrogen dioxide NO2 Not many tests for this gas. The gas is brown. Sulphur dioxide SO2 Test 1 Bubble gas through a solution of potassium dichromate (VI) dissolved in sulphuric acid. The solution turns from orange to green. Test 2 Bubble gas through a solution of potassium manganate (VII) dissolved in sulphuric acid. The solution turns from purple to colourless. Tests for Ions Ion Formula Test Observations Carbonate CO32- Test 1
Enthalpy of formation of calcium carbonate
EXPERIMENT 6 Enthalpy of formation of calcium carbonate Objective To determine the enthalpy of formation of calcium carbonate Procedures A. Reaction of calcium with dilute hydrochloric acid . 1.0909 g of calcium metal was weighed out accurately. 2. 100 cm3 of approximately 1 M hydrochloric acid was pipetted.and placed in a plastic beaker. 3. The initial temperature of the acid was determined 4. The weighed calcium was added into the acid and stirred thoroughly with the thermometer until all the metal had reacted. 5. The maximum temperature attained by the solution was recorded. 6. The experiment was repeated with 1.0538g calcium metal. Results: Experiment no. 2 Mass of Ca used/ g .0909 .0538 Initial temp. of solution/ ? 27 26 final temp. of solution/ ? 55 52 Temperature change/ ? 28 26 Calculations and Discussion: . What does the term "heat of formation" of a substance mean? Heat of formation refers to the heat change when one mole of a substance is formed from its constituent elements is their standard states under standard conditions. 2. What are "standard conditions" for thermochemical calculations? Standard conditions is defined as elements or compounds appear in their normal physical states at a pressure of 1 atm (101325 Nm-2/760mmHg) and at temperature of 25 oC (298 K).Moreover, the solution should have unit activity(1mol dm-3 ). 3. Write
