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GCSE: Organic Chemistry
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H H H Propanol: H - C - C - C - O - H = C3H7O-H H H H C-H: 7 413 = 2891 C-C: 2 347 = 694 C-O: 1 335 = 335 O-H: 1 464 = 464 Total = 2891 + 694 + 335 + 464 = 4384KJ/mol H H H H Butanol: H - C - C - C - C - O - H = C4H9O-H H H H H C-H: 9 413 = 3717 C-C: 3 347 = 1041 C-O: 1 335 = 335 O-H: 1 464 = 464 Total = 3717 + 1041
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I have decided to change my method slightly in the real experiment. I am going to weigh the burner after it has increased in temperature by 40?C I have chosen do this because I do not know whether the other spirit burners will produce more energy, which could make the water reach boiling point, and this would affect the results from the experiment. Also this way I am not required to time the experiment, as all the burners will transfer the same amount of energy.
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Therefore changing the way and the amount of burning the chain itself does, if we vary the length of the chain we can see how the results vary and how much energy each alcohol gives out in a certain period of time. Also for every carbon added there is a H2 added aswell. Size of Container : The size of the container is a factor involved in this experiment, for instance I cannot put more than 100cm3 in a 100cm3 container.
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I expect a change in energy, this will be shown by a change in the water temperature. This will be measured by using the point at which no flame is visible. The change in temperature will be measured by a thermometer, accurate to one degree centigrade. Then the energy given out by the alcohol will be calculated by using the following formula, Energy = mass of water x change in temp x specific heat capacity, the result of this energy given by this equation will be plotted on a graph against the number of carbon's in carbon-carbon chains.
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They have a good variety of sizes and are definite in their sizes. Human errors could be made if any of the other factors are used such as when measuring distances or the temperature rise but the margin of error is greatly reduced when using this factor. It allows me to devise a clear hypothesis, which can be directly compared to my actual results to see how accurate and efficient the method of my experiment really is. As the size of the alcohol increases more energy is produced and released.
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To find out which of these four alcohols: ethanol butanol propanol pentanol is the best fuel to use and also which, uses the least amount of fuel to boil a certain amount of water.
Butanol is a solvent for lacquers, resins, abd other coatings and components of hydraulic break fluid. 4) Ethanol: - is a clear, colourless liquid with a characteristic, agreeable odour. In more concentrated solutions it has a burning taste. Ethanol's molecular structure is CH3CH2OH is a group of chemical compounds whose molecules contain a hydroxyl group, -OH, bonded to a carbon atom, just like all the other alcohols above. Ethanol is made from cellulosic biomass materials instead of traditional feedstock's (starch crops)
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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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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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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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These are metals. Covalent- the sharing of electrons between atoms, completing it's outer shell. These are non-metals. An example is methane where four hydrogen shares an electron with a carbon atom. When some bonds are broken it is due to the energy which is supplied to the chemicals, these are endothermic reactions. When new bonds are formed energy is released, these are exothermic reactions. When new bonds are formed the energy produced by an exothermic reaction can be calculated, This formula is: Enthalpy change = Mass (volume of water) x SHC x Temp. rise (of water)
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in the formation of 1 mol of product. Below is the various types of bonds involved in the reactants in the combustion of methanol: (2CH3OH+3O2==>2CO2+4H2O): Reactant Product Bond Bond energy Amount Total H-C 412 6 2472 C-O 360 2 720 O-H 463 2 926 C-C 348 0 0 O-O 496 3 1488 Total 2079 13 5606 Bond Bond energy Amount Total H-C 412 0 0 C-O 360 4 1440 O-H 463 8 3704 C-C 348 0 0 O-O 496 0 0 Total 2079 12 5144 From this we can now tell that the total amount of energy released from burning a mol of methanol is only (5606-5144/2=)
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The beaker will also be heated, diverting some of the heat energy away from the water. I also predict that the heavier one mole of the alcohol is, the greater the molar heat of combustion will be. This is because the heavier the mole, the more bonds there are, and the more heat energy is required to break them, resulting in a higher heat of combustion. I predict that my line on my graph of results will be relatively straight. To help explain this, when the alcohol reacts with oxygen; water and carbon dioxide are produced.
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1 x C-O is 1 x 358 = +358 1 x O-H is 1 x 464 = +464 3 x O=O is 3 x 498 = +1494 TOTAL = +4728 = -6004 Heat of Combustion = +4728-6004 ?H = -1276 kJ mol -1 2.) Propanol H H H 1 H C C C O H + 4.5O=O 3=O=C=O + 4O H H H H H Bonds Broken (ENDOTHERMIC) ?H = + Bonds Formed (EXOTHERMIC) ?H = - 7 x C-H is 7 x 413 = +2891 6 x C-O is 6 x 805 = -4830 2 x C-C is 2
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I will do this by making the main factor initial and final masses of all four of the fuels. I will need this for the final formula. After this, I will heat the water. I will take the initial and final temperature of the water. I am to heat the water until we reach a 20?C rise in temperature. We then stop the experiment when we reach this temperature rise. We also work out the change in mass and the change in temperature in the water.
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The combustion spreads from the ignition source to the adjacent layer of gas mixture; in turn, each point of the burning layer serves as an ignition source for the next adjacent layer, and so on. Combustion terminates when equilibrium is achieved between the total heat energies of the reactants and the total heat energies of the products. Combustion may also emit light energy, mostly in the infrared portion of the spectrum. The light emitted by a flame arises from the presence of particles in electronically excited states and from ions, radicals, and electrons.
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It takes 4.2J/kg, (this is the specific heat capacity of water) to raise 1g of water; therefore to calculate the energy released by each alcohol we have to use the sum: ENERGY RELEASED = mass of water x temperature rise x 4.2J. Heat of reaction Chemical bonds are forces of attraction between the atoms or molecules in a substance. Energy is needed to break these bonds and energy is released when new bonds are made. In a chemical reaction bonds between atoms in the reactant molecules are broken and new bonds are made.
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