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GCSE: Organic Chemistry
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Overall I don t think that either of the sources is terribly useful, however I feel that source C is slightly more useful and seems more reliable than source B. 3) I think that as source D was taken by the Government, it was almost definitely a piece of propaganda. Source 19 (A3 booklet) a poster from the Government is similar to this. Because of this it is not a reliable, and therefore useful source. Although it is a useful source to show us what the Government at the time were trying to put across.
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Breaking bonds need less energy than is needed to form bonds - exothermic reaction. Bigger molecules use high energy to be broken. Methanol and Ethanol have differences as Methanol melts at a higher temperature and boils at a lower temperature than Ethanol. Higher alcohols which include Butanol and Propanol have a higher molecular weight and this is why Butanol is used in perfumes. Ethanol, which is sugar based, with its low freezing point, has a specific use as antifreeze for cars and other vehicles. Methanol + Oxygen > Carbon Dioxide + Water 2CHOH + 3O > 2CO2 + 2H2O Breaking (6x413)
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In the column the hottest temperature will be at the bottom and the coolest at the top. This means that the parts that have boiled from the heating will be gaseous and rise up the column and those that have not will still be in liquid form and will sink to the bottom. As the different gases rise up the column they will condense at different points and as such the liquids they form can be collected. These are called 'fractions'. This process works because the fractions each have their own 'specific boiling point range'. The fractions do not have an exact boiling point temperature, as they are mixtures of lots of hydrocarbons, rather than just one type.
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An alcohol is a water molecule with an alkyl group in place of one of the Hydrogen atoms. This is shown here in the example of ethanol: Alcohols are told apart by the number of carbon atoms they have. For example Methanol has 1 carbon atom, Ethanol has 2 carbon atoms, Propanol has 3 carbon atoms and Butanol has 4 carbon atoms. The table continues up to Eiconol, which has 20 carbon atoms but we are only concerned with the first 4 as they are the ones I will be using in the experiment. Alcohols are written with OH on the end as in CH OH (Methanol)
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Internet - www.helicon.com CD ROM - Encarta Class book - GCSE Chemistry by Bob Mcduell Preliminary Results Equipment: * Spirit Burner * 4 Alcohols (methanol, ethanol, propanol, and butanol). * Retort Stand and clamp * A large copper container. * Thermometer * 100 ml of cold water * Stop watch * Balances * Heat resistance mat 1) First assemble the equipment as in diagram above. 2) Weigh the filled spirit burner. 3) Measure out 100 ml of cold water and put it into the copper container, and attach to clamp and stand. 4) Take the temperature of cold water. 5)
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To determine which alcohol, out of ethanol and propanol, is the better fuel. By calculating the enthalpy change of combustion for ethanol and propanol I will find how much energy is released per mole of each alcohol.
is the enthalpy change when one mole of an element or compound reacts completely with oxygen. The combustion of an alcohol is an exothermic reaction, which means that the enthalpy of the products is less than that of the reactants, meaning that the energy will have a negative value. The chemical equations for the complete combustion of ethanol and propanol are shown respectively: C2 H5 OH + 3O 2 2CO2 + 2H2 O C3 H7 OH + 4.5O 2 3CO2 + 4H2O We can use this information to calculate the enthalpy change of combustion using Hess's Law and the enthalpy cycle.
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Whenever chemical reactions occur, energy is transferred to or from the surroundings. Energy must always be supplied to break bonds and energy is always released when bonds are formed. During a chemical reaction, old bonds are broken and new bonds are formed. Energy must be supplied to break existing bonds. Therefore, bond breaking is an endothermic process. An endothermic reaction is one, which takes in energy from its surroundings. Usually in the form of heat, which is indicated by a fall in temperature. Endothermic reactions are very rare and hard to spot.
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= 3338 Energy out 3338 - 2803 = 535 = 535 kJ Ethanol C2 H5 OH + 2O2 ? 2CO2 + 3H2O H H O = O ? ? O = O 496 x 3 743 x 4 + 463 x 6 H - C - C - O - H O = O ? ? H H C - H C - C C - O O - H ( 412 x 5 ) ( 348 ) ( 743 ) ( 463 ) 2060 + 348 + 743 + 463 3231 + 1488 = 4719 5750 - 4719 = 1030 kJ Propanol C3 H7 OH + 4.5O2 ?
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To find out how much energy is produced when burning two hydrocarbons, Ethanol and Paraffin. I will be burning these hydrocarbons to heat up a beaker of water.
Ethanol has two carbons. The molecular formula is C2H5OH. The structural formula is shown below. Ethanol is not a strictly a hydrocarbon because the molecule contains oxygen as well as hydrogen and carbon. When hydrocarbons are burned in air an exothermic reaction occurs forming carbon dioxide and water. The amount of combustion can vary due to the amount of oxygen present if there is lack of oxygen this is known as incomplete combustion. This is the equation for incomplete and complete Combustion. If there is not enough oxygen present to completely burn the fuel to carbon dioxide and water, other products may form.
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An Investigation into How the Amount of Heat Produced By Burninga Fuel Depends On the Mass of the Fuel Burnt
805kJ/mol O = O 498kJ/mol Bonds Broken: 1x C - C 1x +347 1x C - O 1x +360 1x O - H 1x +464 5x C - H 5x +431 3x O = O 3x +498 Total = +4730 Bonds Made: 4x C = O 4x -805 6x O - H 6x -464 Total = -6004 ?H = 4730 - 6004 = -1274Kj/mol�� Calculations: H H ? ? H - C - C - OH + 3O = O ==> 2O = C = O + 3O ?
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I then took the temperature of the water in the copper can. I put the fuel on a heat proof mat on the table and put the copper can of water in a stand, clamped so that the top of the fuel pot was 130 millimetres away from the bottom of the copper can. I made a shield around the stand, fuel and copper can, using heatproof mats so that the heat didn't travel away from the copper can. I then took the lid off of the fuel pot and lit the wick straight away using a splint.
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Then, using a splint lit from the Bunsen burner, I will light the spirit burner. I then will let it burn until the temperature of the water has risen by 10o, keeping an ye on the thermometer all the time. When the desired temperature has been reached, I will put out the flame by replacing the lid. Before recording the new temperature of the water, I will watch the thermometer for another 30 seconds, and then record the highest temperature it reads.
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* Measuring cylinder Method I will need to collect all of the above apparatus and then put it together like in the diagram below. I will weigh the alcohol I will be burning and then put it under the copper calorimeter. I will use a measuring cylinder to measure out 100cm3 into the copper calorimeter. I will light my Flame, which will be 5cm under the calorimeter. I will use my thermometer to determine the temperature and then go up to 60?c because that is how much I will change the temperature by.
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and increase the temperature of the water, which I am going to use to measure. Heating the water will produce accurate results in the temperature rise. I am using the homologous series of alcohols because they have similar structures. Structure is what bonds and atoms a fuel contains. Below are the structures of the fuels I am using: - METHANOL ETHANOL PROPANOL BUTANOL PENTANOL HEXANOL The homologous series of alcohols have similar structures because they all increase their number of carbon and hydrogen atoms in a pattern.
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As alcohol's are very dangerous and highly flammable I will wear my safety goggles at all times. I will need to keep all lose items off clothing tucked in. the lids on the alcohol's must be kept on at all times to prevent evaporation or any spillage's. Apparatus � Clamp � Beaker � Crucible � Measuring cylinder � Weight scales � Aluminium soft drinks can � Thermometer The method that I will use is as follows... � Measure 150cm of water into a can beaker. � Place the can into the grasp of the clamp stand. � Record the starting temperature of the water.
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The other form of bonding is covalent where atoms share electrons to complete their outer orbit. For example Methane, where four hydrogen atoms each share an electron with a carbon atom. Apparatus * Stop clock * Thermometer * Boiling tubes * Measuring cylinder * Spirit burners containing the fuels * Balance * Matches * Clamp stand and boss head * Splints Method * Gather all the apparatus as above * Set all the apparatus as shown below * Fill up a measuring cylinder with 20cm cubed of water and pour it into the test tube * Make sure the test tube is 12 cm off the surface below * Decide what fuel to test and how long should it be tested for.
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Investigate and compare the amount of energy released during the combustion of alcohols with practical and theoretical combustions.
To calculate the practical results for change in chemical energy I had to first convert the amount of alcohol type burnt into KJ/mol. This was done using the following formula: Amount of energy given off [Energy] ___________________________________ x number of grams per mol Amount Burned (g) I was given the following bond values as below: Bonds Value of Bonds (KJ/Mol) C-H 412 O=O 496 C=O 743 O-H 463 C-O 360 C-C 348 Results Ethanol C2H5OH + 3O2 2CO2 + 3H2O H H O=O O H-O-H | | || H - C - C - O - H O=O C=O H-O-H | | O H H O=O || H-O-H C=O Theoretical H-C x5 = (412x5)
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Find out the difference in energy that is given out by the alcohols Methanol, Ethanol, Propanol and Butanol when they are burned under a tin of water for 3 minutes.
boils and if you have more it doesn't get hot enough to record a difference between the alcohols in the 3 minutes. In order to make my results more accurate I will put the metal can of water as close to the flame as possible to make sure as little heat as possible is lost into the surrounding atmosphere. I will weigh the spirit burner before and after the experiment so I can see how much alcohol has been lost.
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and then will combust later, making this experiment an exothermic reaction. Therefore the long chains of hydrocarbons produce more energy than smaller chain molecules as the long chain breaks in to smaller hydrocarbons meaning theirs more, making the boiling point decrease, which makes them more flammable, less viscous, and more volatile. Therefore I would expect that when the alcohol's is being burned and producing heat energy, carbon dioxide, and water will be produced meaning the alcohol would lose some mass which would evaporate into the air.
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Before the experiment you have to check all of the risks involved. Risk Assessment Chance of water/ alcohol Wear goggles Spraying in eyes Burned Hair Tie hair up Setting Bench on fire Use bench mat I will do each experiment twice to make sure the results are reliable and I can do some averages. The equipment I will need to do this experiment is: * Clamp * Boss * Stand * Tin with water * Thermometer * Bench mat * Alcohol (methanol, Ethanol, Butanol and Propanol)
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He never discloses any emotions or information to Horatio, seen as his only friend, and the love of his life betrays him. This secondary information is another reason Shakespeare includes to produce pathos, and it works just as he wishes. His views expressed to the audience before this are yet again questioning his inability to act. Hamlet is assured of the king's guilt yet he still doesn't act. Audience sympathy may be faltering here if it wasn't for the dramatic irony that they know Hamlet is about to be tested.
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To investigate the amount of heat released in the burning of fuels: ethanol (C2H5OH), propanol (C3H7OH) and butanol (C4H9OH).
For this reason the reactant energy is higher than that of the product. BOND ENERGIES To calculate the ideal energy released through such an experiment it is necessary to know the amount of energy that is required to break each bond bonds. TYPE OF BOND BOND ENERGY (kJ/mol) C-H 410 C-O 360 O-H 510 O=O 496 C=O 740 C-C 350 --------------------------------------POSSIBLE VARIABLES----------------------------------- -- Type of Alcohol (Selected Variable) -- Container size/Volume of water -- Type of container -- Volume/Mass of alcohol -- Distance between wick and container -- Starting temperature of water FAIR TEST?
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The equation for this experiment is as follows:- CH3CH2OH + 3O2 ??Combustion??? 3H2O + 2CO2 Ethanol + Oxygen Water + Carbon Dioxide Apparatus 1x Stand 1x Boss 1x Clamp 1x Tin Can 1x Heatproof Mat 1x Crucible 31.5mls Fuel(Ethanol)divided into:- 3x 0.5mls 3x 1mls 3x 2mls 3x 3mls 3x 4mls 15x 100mls Tap Water 1x Thermometer Apparatus Diagram Method I plan to use the "volume/mass of fuel" variable to prove whether the volume/mass of fuel affects the energy output. I chose this variable because it seemed to be a useful thing to learn and know about.
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We will put this under the clamp stand, which is holding the boiling tube of water and a thermometer. We will then time 2 minutes and find out how much the temperature has risen. We will repeat the experiment four times to calculate an average. To make it a fair test we will keep the water volume at 40cm3, the same distance from the flame to the water and fresh water at the start of each experiment. Results: Temperature in �C Tests Before After Change 1 24 30 6 2 22 28 6 3 21 27 6 4 23 28 5 Conclusion: In 2 minutes the ethanol increased its temperature by 1?c from 5?c to 6?c.
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Method The Diagram below shows the apparatus set up for burning a liquid fuel. - Put 100cm3 of cold water in a copper can and record its temperature - Support the copper can approximately 2cm over a spirit burner containing the fuel you are going to test. - Arrange a draught system to reduce energy loss. - Weigh the spirit burner - Replace the spirit burner under the copper can and light the wick - Use the thermometer to stir the water al the time it is being heated.
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