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GCSE: Organic Chemistry
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Cosmetics are things that many people want, but they do not necessarily need it, so when the cosmetic industry have to test on animals to meet the need of demanding customers, the animal testing argument prevails. Are humans selfish and care about the appearance of themselves than an animal that has to battle through their short life because someone wants to look better? What is an ester? An ester is an organic compound that is formed from an organic acid and alcohol.
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* Heat Loss - Heat is always lost during this reaction. Some of the heat will not be used to heat the water in the beaker, altering the overall result. Therefore heat proof mats are used to keep it in as much as possible. * Equipment - Changing equipment may alter the result in some way due to flaws in the apparatus, which will alter the result. * Beaker Material - The tin can must always be used to avoid using both the glass and the tin, changing results as they both conduct heat differently.
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Planning: Aims: In this experiment, I'm trying to prove that the higher reactivity metals in the metal solution will be able to replace the lower reactivity metal pieces. Also to prove the metal, magnesium, will have the highest reactivity out of the five different metals. Then I believe that after the experiment we should be able to learn which metal is reactive and be careful with them in the future time. Variables: 1. The metal pieces used in the experiment. 2. The metal solutions used in the solution. Control Variables: 1. The measurement of metal solutions for the experiment. 2.
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Esters. Esters are formed from an alcohol and carboxylic acid; this is an example of esterification. I am going to write about the chemical reactions of when an ester is made, the ethics of animals used for testing cosmetics, what an emollient is and I w
The most common ester is ethyl ethanoate (ethyl acetate). Ethanol (alcohol) + ethanoic acid (acid) = ethyl ethonate (ester) + water. This is the formula- CH3CH2OH + CH3COOH ? CH3COOCH2CH3 + H2O. This is a colourless liquid and has a sweet smell. Ethyl ethonate has many uses, such as artificial fruit essences and aroma enhancers, artificial flavours for confectionery, ice cream and cakes, as a solvent in many applications (including decaffeinating tea and coffee) for varnishes and paints (nail varnish remover), and for the manufacture of printing inks and perfumes. Ethyl butanoate is an ester with the chemical formula- CH3CH2CH2COOCH2CH3.
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take a long time to reach this temperature and the dependant variable would still change clearly The independent variable is the variable that is changed to affect the dependant variable. The independent variable is the size of alcohol used or the number of carbon atoms (which determines the alcohol). The dependant variable is the variable that changes depending on the independent variable, which is the change in mass. This is used to calculate the energy released in the reaction. Preliminaries: The reason of doing a preliminary was to confirm the decisions made on the controlled variables, to see that a reasonable mass difference occurred and if not the independent variable which has to be increased on decreased.
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The base I will be using is sodium carbonate. The alkalis are substances which when dissolved in water furnish hydroxyl ions. e.g.: NaOH = Na+ + OH - According to the Bronsted-Lowry theory the definition of an acid is a proton donor and a base is a proton acceptor. Usefulness of titrations: 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.
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As the oxygen builds up in the top of the burette it will force the water down, thus allowing us to measure the amount of oxygen in the top of the burette. The burette holds a maximum of 50cm3 so the amount of gas collected cannot exceed this. There are two methods of measuring the rate of reaction. One is to measure the time it takes for the reaction to produce a certain volume of oxygen and the other is to measure the amount of oxygen produced in a certain length of time.
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New bonds form between carbon and oxygen in C02 and between hydrogen and oxygen in H20. Between successive alcohols, the structural difference between each alcohol is of course the CH2 group of atoms. So each alcohol has one C?C bond and two C?H bonds more than the previous alcohol. From my previous understanding and knowledge, I know that the first step in a reaction is the supply of energy to break a bond between two atoms. Energy is only released to the surroundings when the new bonds are formed.
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An exothermic reaction gives out energy to heat its surroundings while an endothermic reaction cools its surroundings by taking in energy. Bond enthalpy calculations can be used to give ?Hc Reactions involve bond breaking (which is an endothermic process) and then new bond making (which is an exothermic process). During an exothermic reaction the overall enthalpy of the reacting system decreases. This means that ?H is negative as energy from the reactants forming is transferred to the surroundings (air, test tubes, car engines, etc)
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Their earliest form was that of a simple stone slab with incised parallel lines. The lines served to mark the place values. The earliest known counting table is from the island of Salamis in Greece. The latest surviving counting table is from the end of the 16th century and is in a museum at Strasbourg (Pullan 53). The only real difference between the early and later forms is the direction of the place value lines: horizontal or vertical. The medieval European form is the most well documented, in part because the English Exchequer only stopped using the counting table for tallying tax payments and the like in 1826 (Pullan, 27).
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Probably the most conductive container available for use in the classroom is a calorimeter. As well as not wasting energy in the heating of the container, I could also try to stop heat from escaping the top and edges of the container by covering it with a fitting lid. I will try to prevent the wind from blowing the flames to a different direction so all the windows must be shut. HYPOTHESIS More energy is released as more bonds are formed, below is the list of approximate energy required to break and form all bond involved in burning alcohols TYPE OF BOND ENERGY REQUIRED TO BREAK THE BOND (j)
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We will be using water as our substance with a known specific heat capacity. Prediction I predict that the longer the hydrocarbon chain the more energy will be transferred to the water, therefore fewer moles of fuel will be used to achieve the same temperature rise. So as the number of carbon atoms increases the enthalpy of combustion will become more negative. I think this because as you add a H-C-H bond you increase the energy required to break the bonds by 826KJ/Mol.
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The functional group of the Homologous series (the OH group) is in the same position on all of the alcohols we are using, therefore this will not effect our results. I carried out a trial experiment, to try and asses where error occurred within the experiment, using Methanol and Hexane. From the errors that occurred within the trial experiment I can adapt our final method to improve this error. The experiment that I used is outlined below. Apparatus * A small copper can which will act as a calorimeter.
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= C4H9OH * Butan-2-ol = C4H9OH I have chosen these alcohols because I will have a chain containing 1 carbon atom, 3 carbon atoms, 4 carbon atoms and 5 carbon atoms. I have also decided to use structural isomers of two of these, Propanol and Butanol. (Propan-1-ol and propan-2-ol and Butan-1-ol and butan-2-ol). This will allow me to compare the enthalpy of combustion of increasing chain length and the structural isomers of some of these alcohols. Alcohol structure Methanol H H | / H - C - O | H Propan-1-ol H H H | | | H - 1C
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> To perform a detailed analysis of the strategic financial and non-financial implications of Sainsbury's switching to another fuel source > To give a recommendation based on our findings 1.4 Recommendation Having carried out a SWOT analysis, an investment appraisal, and considered non-financial implications of adopting a greener fuel source, this report recommends Sainsbury's would add value to their business by switching to Natural Gas in the medium term. 2. Research Agenda and Assumptions Made 2.1 Agenda In carrying out this investigation, the group agreed on a set of guidelines and basic philosophy to abide by in order to maximise the integrity and significance of our report.
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Method 1. Set up all the apparatuses; design a suitable draught system that can reduce energy loss to the minimum. 2. Add 200cm 3 of cold distill water into copper calorimeter, measure and write down the temperature. 3. Weight the spirit burner, including the alcohol fuel and the burner cap. Record the weight. 4. Replace the Bunsen burner under calorimeter and light the wick. 5. Go on heating until the temperature has risen by about 15-20C. 6. Extinguish the burner. Record the temperature on thermometer. 7. Weight and record the mass of spirit burner with liquid fuel that has been burned. 8.
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By using the bond enthalpies this can be done. The estimation for the enthalpy of combustion, using the bond enthalpies are worked out below for each of the alcohols. Methanol CH3OH (l) + 11/2O2 (g) CO2 (g) + 2H2O (l) Energy required in Bond Breaking (KJ mol -1) Energy required in Bond Making (KJ mol -1) 3 x (C-H) 3 x (+413) = 1239 2 x (C=O) 2 x (+740) = 1480 1 x (O-H) 1 x (+464) = 464 4 x (O-H)
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I chose to use water as it is safe, easily obtainable, and has a constant, reliable specific heat capacity of 4.2J/�C. The bonds which are made in a exothermic reaction are forces of attraction between the atoms or ions in a substance. These can be of two types: covalent, in which the atoms share electrons. Examples of this are water and carbon dioxide, which has a double covalent bond because it shares two pairs of electrons are shared. The other type of bonds is ionic, where a metal is involved.
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If only porous rock was present, the oil could get up to the surface, forming shallow lakes. In other places, the porous rock were overlaid by a layer of impervious rock which prevented oil travelling any further and an oil reservoir was created. Natural gas often forms a pocket at the surface of oil reservoirs. What does crude oil contain? Crude oil is a mixture of about 150 different hydrocarbons. Hydrocarbons are compounds that contain only carbon and hydrogen. The majority of hydrocarbons in crude oil are straight chain alkanes, but with the mixture also contains cycloalkanes and arenas.
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Ionic bonding involves two electrons transferring from one atom to the other leaving an electrostatic force between them. The other is covalent bonding where atoms share electrons to complete their outer shell. An example being methane where four hydrogen atoms each share an electron with a carbon atom. In this investigation, I wish to compare heat produced by the alcohols in terms of: Equal masses. Equal numbers of molecules, i.e. per mole. To calculate the theoretical enthalpy of combustion we need to know the energy requiring in breaking a bond. Methanol (CH3OH) CH3OH + 11/2 O2 = CO2 + 2 H2O Bond Av.
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Do fuel cell systems offer a feasible alternative to combustion engines in minimizing the harmful emissions of transport vehicles?
The essay works like a projection of future driving with focus on the likelihood of fuel cell vehicles being a new mode of transport. Based on a study of what allows the fuel cell system to stand out as an alternative to combustion engines and demonstrate recent ingenuity, some conclusions are made in response to the research question. The assertion is made that while fuel cell systems do make a desirable alternative, their success in bringing down the emissions due to road transport is dependent on the marketing and administration of them.
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This will also apply when replacing the lid after the experiment. I will make sure I keep this experiment fair by carefully controlling the variables. My Preliminary Experiments Before I do my actual experiment I am going to carry out some preliminary experiments to help me decide on how much water I should use in the tin, the time I should allow for each experiment and the height above the flame. I will select the most appropriate and the one that gives the best results and best temperature change.
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The aim of this experiment is to compare the amount of energy released when a number of alcohols are burned.
When the burner is closer, less energy is released to raise the temperature of the water, because less heat loss will occur. This is because when the distance is shorter, there is less air in between, so overall, there will be less heat loss to the air during the experiment when the can is closer. Hypothesis Energy changes in reactions are caused by the breaking and making of chemical bonds. Breaking chemical bonds takes in energy and making chemical bonds releases energy.
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Bond enthalpies differ with each type of bond and the exact enthalpy for a particular bond can differ. Average bond enthalpies can be found on the Internet and in data books. We can use bond enthalpies to work out the energy given out by a reaction by comparing the energy needed to break the bonds (endothermic) to the energy given out when new bonds are made (exothermic). We can use these figures to work out the theoretical molar heat of combustion of the alcohols, which I will do later. Average Bond Enthalpies: Bond Type Average Bond Enthalpy (kJ per mole)
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In this report the effects of fire and explosion are examined based on quantitative analysis using calorimetric methods.
In this report the experimental apparatus of the forensic analysis of fire and burning behavior, experimentation and results of their use are disused. The following techniques were employed. * Determination of Flash Point by means of the Pensky-Martins Closed Tester. * Determination of Flame Stability. * Oxygen Index Test. * Determination of Calorific Value by means of the Bomb Calorimeter. The aim of the flash point experimentation was to determine the flash point of several hydrocarbon liquids by means of the Pensky Martins Closed Tester.
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