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AS and A Level: Organic Chemistry
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Five equations you must know for organic chemistry
- 1 Alcohol + carboxylic acid = ester + water (eg CH3OH + CH3CH2COOH becomes CH3OOCH2CH3 + H2O)
- 2 Alkene + hydrogen = alkane (eg CH2=CH2 + H2 becomes CH3CH3)
- 3 Alkene + water = alcohol (eg CH2=CH2 + H2O becomes CH3CH2OH)
- 4 Halogenoalkane + hydroxide ion = alcohol + halide ion (eg CH3Br + OH- becomes CH3OH + Br-)
- 5 Alkene + hydrogen bromide = halogenoalkane (eg CH2=CH2 + HBr becomes CH3CH2Br)
Five facts about alcohols
- 1 Primary alcohols are oxidised into aldehydes and water, which are then oxidised into carboxylic acids. Secondary alcohols are oxidised into ketones and water. Tertiary alcohols cannot be oxidised.
- 2 Alcohols are oxidised by acidified potassium dichromate (H+/K2Cr2O7). This starts off orange and will turn green if it oxidises something (so with tertiary alcohols it will stay orange).
- 3 There are two ways of making alcohols: fermentation and hydration of alkenes. Fermentation is good because it uses renewable resources and does not take much energy, however it can only produce alcohol up to 14% before the yeast die.
- 4 Alcohols are soluble in water as they can make hydrogen bonds with the water. However, the “carbon chain” attached to the OH cannot interact with water and is insoluble. This means that alcohols become more insoluble the longer the carbon chain.
- 5 Alcohols have a very high melting and boiling point compared to alkanes of the same chain length. This is because they can form strong hydrogen bonds with each other that require a lot of energy to break.
Five facts about hydrocarbons
- 1 The longer the carbon chain the higher the higher the boiling point, as there will be more points of contact and stronger van der Waals forces.
- 2 The more branched the carbon chain the lower the boiling point, as the molecules will not be able to pack as close together and will have weaker van der Waals forces.
- 3 Hydrocarbons are insoluble in water as they cannot make intermolecular forces with them.
- 4 Hydrocarbons have low boiling and melting points as the only intermolecular forces that can hold them together are weak van der Waals forces which require little energy to break.
- 5 When processing crude oil (a hydrocarbon), the aim of the game is to get short, highly branched hydrocarbons. This will increase their volatility and make them a better fuel. We do this through: fractional distillation (sorts them into different sizes), cracking (splits long chains into short chains), isomerisation and reforming (makes the chains branched and cyclic).
- Marked by Teachers essays 7
- Peer Reviewed essays 13
mixed reactants will be placed on a paper marked with an "X" * Time taken for the precipitate to form and hide the "X" will be measured and recorded. * The experiment will be repeated for accuracy Apparatus: * 2M Hydrochloric Acid * 0.4 M Sodium Thiosulphate * Distilled Water * Thermometer * Stopwatch * Measuring Cylinders ( 10ml+ 50ml) * Measuring pipette * Conical Flask (100ml) * Marker * (Access to a fume cupboard) Method: Dilution of solutions to lower their concentrations: When diluting a solution, it is important to know that we are not losing any fraction of the solvent by mixing it with distilled water.
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Then we weight the dried product and recorded its melting point. Chemical reaction: Equation 1: Synthesis of Aspirin Preparation of silver chloride: Now I am going to explain the preparation of silver chloride; Materials : (a) silver nitrate (b) sodium chloride (c) cylinders (d) beaker (e) glass rod (f) filter paper (g) Buchner funnel (h) oven etc. Procedure 1. Firstly we had to measure 10 cm3 of silver nitrate and sodium chloride solutions in two separate measuring cylinders. 2.
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Design two experiments, one using titration and one using gas collection to show that H2SO4 is a dibasic acid.5 star(s)
- 1 Gas(dm3) - 2 Gas(dm�) - 3 Gas Average(dm�) To keep the results accurate we will keep all equipment and solutions used the same every time, we will do this experiment 3 times and take the average of the readings, and use this to see if H2SO4 is dibasic, theoretically we should measure 0.6dm3, although we may not get this exact reading for many reasons: * Inaccuracy when measuring solutions/weight of Mg. * Impurities in the solutions used e.g: Concentrated H2SO4:"Purity: 95%-98% Pure"  * If all the reactants weren't used up in the reaction.
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Beta particle is emitted when a heavy element decays with atomic number of above 82 decays. Alpha radiation reduces the ratio of protons to neutrons in the parent nucleus. A beta particle is emitted when there is too many neutrons, a neutron decays into a proton, an electron and an antineutrino. Difference between nuclear fission reaction and natural radioactive decay: The fission of a nucleus involves splitting it into two more or less equal fragments. For example uranium, in which it yields two or more lighter nuclei and a large amount of energy. If an atom of U- 235 is given sufficient energy through the absorption of one neutron, it enters an excited state and begins to oscillate.
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is a constant known as the extinction coefficient. The absorbance A and extinction ? are sometimes defined in terms of the natural logarithm instead of the base-10 logarithm. Methodology: Colorimetric Analysis: At the beginning, 4cm3 decarbonated cola was transferred into a 100cm3 volumetric flask and diluted with distilled water. After, 25.0cm3 of the sample, 0mM (blank), 0.1mM, 0.2mM, 0.4mM and 0.6mM of phosphate standards (KH2PO4) were put into six 50ml volumetric flask separately. Then, 5ml of vanadate-molybdate reagent was added to each flask and all of the flasks were diluted with distilled water. Finally, the absorbance of each solution was measured at 400nm and recorded.
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The I2 not yet reacted would then be titrated against thiosulphate solution, like the first equation, to determine its amount. This method is a kind of back titration. It is the excess amount of substance which is being titrated, but not the object being studied. This method is used when the direct titration of the object being studied is not suitable, which is why back titration is used in this method. Procedure 1. 0.682g of potassium iodate solid was weighed out.
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