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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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Esterfication. he purpose of this lab is to achieve a specific odour through the process of esterification where carboxylic acid and alcohol react to produce an ester and water with the assistance of heat and a catalyst such as sulphuric acid.
The carboxylic acid family is highly polar since oxygen is slightly negative in comparison to hydrogen which is slightly positive in terms of electronegativity. This means that acid's can be expected to have a higher melting point and boiling point in relation to alcohol's because of its strong intermolecular force which in this case is the hydrogen bond. The reason as to why acids have high melting points and boiling points relative other molecular compounds is because of the fact that more energy or heat is required in order to overcome the hydrogen and oxygen attractions.
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The aims of this experiment are to prepare urea-methanal from urea and methanol to compare the physical properties between the synthesised urea-methanal (thermosetting plastic) and polyethene (thermoplastic)
Dilute sodium carbonate solution was added to the boiling tube after the product turned to solid. 5. The wooden stick was taken out and if the polymer was stuck to the wooden stick, no extra procedures were needed to take the polymer out from the boiling tube. 5. If the polymer was not stuck to the wooden stick, a hammer was used to break to boiling tube wrapped with newspaper. 6. The polymer was carefully taken out using a pair of tongs.
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Hydrolysing Organic Halogen Compounds. The purpose of this experiment is to find out how the rate of the hydrolysis of an organic halogen compound depends on (1) the identity of the halogen atom (2) the nature of the CH skeleton.
* Silver Nitrate (AgNO3) * New Clean Test tubes; * Clock Experiment Procedure and Observations 1. Six test tubes were prepared with 2cm3 of ethanol and 5cm3 of silver nitrate added into it. 2. Six drops of the each of the six chemicals subjected to analyze are added into the test tubes. 3. The test tubes were shook well and placed on a test tube rack. 4. Times required for precipitates to appear were taken down. 5. Observations were taken down. Results Recorded Reactant# Time for precipitation to appear (min) Observations A. 1-chlorobutane >30 No observable change B.
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Apiece costs about �3 each! Label it with a pencil at the top. Smudging the TLC plate with finger prints or dirty hands Low Hold by the edge or top corner or use gloves. Draw a straight line about 1 cm above the base of the TLC plate using the pencil and ruler. Pressing to hard with pencil resulting in piercing through the plate Low Place the TLC plate on a table and proceed with pressure force labeling Spot the plate with a small amount of Caffeine make the spot as small as possible.
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Basic Idea: a. Copper carbonate will be heated b. Decomposition will occur c. A gas will be released and it will be collected. d. The volume of the gas that will be collected will give us an indication as to which equation is correct. Calculations - Hypothesis: (Essential Information) 'At room temperature, 25�C and atmospheric pressure at 1 atmosphere, I mole of any gas will occupy a volume of 24 dm�.' This information will be used to calculate how much copper carbonate will be required for decomposition in order to obtain a sufficient amount of carbon dioxide gas to fit the measuring cylinder that will be used.
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In order to get this ratio, you would have to use equal volumes of the two gases. Because water is cheap, it would seem sensible to use an excess of steam in order to move the position of equilibrium to the right according to Le Chatelier's Principle. In practice, an excess of ethene is used. This is very surprising at first sight. Even if the reaction was one-way, you couldn't possibly convert all the ethene into ethanol. There isn't enough steam to react with it. The reason for this oddity lies with the nature of the catalyst.
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The smaller the time needed, the faster the rate of hydrolysis. Hydrolysis is a chemical process in which a certain molecule is split into two parts by the addition of a molecule of water. One fragment of the parent molecule gains a hydrogen ion (H+) from the additional water molecule. The other group collects the remaining hydroxyl group (OH-). Types of halogen compound Haloalkanes: organic compounds having one or more halogen atoms replacing hydrogen atoms in alkanes. The general formula of haloalkanes: CnH2n+1X. Classification of haloalkanes: Halobenzenes- organic compounds in which the halogen atom is directly attached to a benzene ring.
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Vitamin C. I will investigate whether orange juice contains the most Vitamin C and how I can speed up and slow down the oxidation process of Ascorbic Acid.
DCPIP (blue) + H+ ----------> DCPIPH (pink) DCPIPH (pink) + Vit C ----------> DCPIPH2 (colorless) However I will also be using Iodine as an indicator to see if it is a better one than DCPIP. DCPIP oxidises very easily and therefore it will take more DCPIP to oxidise vitamin C because it is already oxidizing. DCPIP is an oxidizing agent so it will reduce something else e.g. the Ascorbic acid. The amount of ascorbic acid can be determined by a redox titration with a standardised solution of iodine. The iodine is reduced by the ascorbic acid to form iodide. As shown in the other half of this redox equation.
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This means that one mole of sulphuric acid can release two moles of hydrogen ions, H+, when it reacts in aqueous solution. The reaction of sulphuric acid with sodium hydroxide solution forms sodium sulphate solution, in which both of the acidic hydrogen's react with hydroxide ions. 2NaOH(aq) + H2SO4(aq) --> Na2SO4(aq) + 2H2O(l) Method (a): by measurement of the gas Apparatus: -the quantities of chemicals you would use and calculations to show how you decided these quantities. 1. Set up apparatus as shown below.
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Photosynthesis consists of two stages: a series of light- dependent reactions, which are temperature independent and a series of light independent reactions, which are temperature dependent. Increasing light intensity can increase the rate of the light dependent reactions. Increasing the temperature can increase the rate of the light independent reactions. Photosynthesis begins with the absorption of light by pigments. Chlorophyll and other pigments known as carotenoids absorb different wavelengths of light, which broadens the spectrum of light energy that can be fixed through photosynthesis.
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sodium hydroxide to acetylsalicylic acid and heat the mixture to hydrolyze the acetylsalicylic acid as hydrolysis reaction occurs at a very slow rate at room temperature and increase the temperature can increase the rate of reaction. After that, the resulting solution contained acetic acid, salicylic acid water and excess sodium hydroxide which was unreacted. Then we can titrate sulphuric acid with the resulting solution to find out the amount of excess sodium hydroxide and therefore the amount of sodium hydroxide used to hydrolyze the acetylsalicylic acid.
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* Eye protection is to be worn throughout, to protect eyes from chemicals. * Bags, and other possible obstructions, should be kept away from the working area, to prevent tripping, etc. * Glassware should be handled with care, so as to prevent breakages. In the event that glass is broken, it should be cleaned up immediately, and carefully, along with any spillages. * More generally, spillages should be dealt with immediately, and in accordance with any precautions necessary for the chemicals being used.
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The colour of the oxidizer is initially orange and the colour changes to dirty green upon mixing. The oxidation reaction produce a large amount of heat which heats up the reaction mixture. The flask used for the reaction is situated in an ice bath to cool down the mixture to prevent reactants or products being boiled away. After addition of the oxidizer, the products are collected by simple distillation. To increase the yields of reaction, the oxidizer is used in excess to make sure reaction is complete. Distillates of boiling point ranged from 54 �C to 58 �C should be collected as products.
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Then Fe2+ mass in 2nd solution - Fe2+ mass in 1st solution = Mass of Fe2+ originally in the solution. This experiment will only give me the Mass of Fe2+ in the solution, so the Fe3+ will need to be worked out by subtracting the Mass off the Fe2+ from the 200cm3 solution used at the beginning. Manganate to iron is a 1:5 ratio. The concentration of manganate at any time is 5 x less than Fe2+. 2 The equation for this reaction is MnO4- + 5Fe2+ + 8H+ + 5e- Mn2+ + 5Fe3+ + 5e- + 4H2O Equipment 200cm3
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Emergency Eye contact: Immediately flush the eye with water. If irritation persists, call for medical help. Skin contact: Wash off with soap and water. If swallowed: Call for medical help. Disposal Very small amounts can be flushed down the sink unless local rules prohibit this. Spills should be neutralised with soda ash. Protective equipment Safety glasses. 1 2, 4 DPNH/Brady's reagent Add a few drops to Brady's reagent (2, 4-dinitrophenylhydrazine solution) to the unknown. Brady's reagent detects the carbonyl function of an aldehyde and ketone. Yellow/orange precipitate forms with aldehyde or ketone. Principal hazards 2,4-DNPH is potentially explosive when dry and may decompose rapidly or explosively if heated or subject to shock.
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bond in the alkene, in this reaction it acts as an electrophile. The ? bond breaks and the electron pair form a new covalent bond to the bromine atom. The bromide ion and carbocation produced then react to form a dibromoalkane. This is an electrophilic addition reaction. The mechanism is shown below: Outcome for a phenol: A phenol will also decolourise bromine water, but will also produce a white precipitate of 2, 4, 6 - tribromophenol. Explanation: The oxygen atom in the hydroxyl group has a lone pair of electrons, this lone pair can move onto the delocalized benzene ring, therefore increasing electron density (especially at the 2, 4 and 6 positions).
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ions. MnO4- + 8H+ + 5e- ? Mn2+ + 4H2O Ethanedioic acid is oxidised to form carbon dioxide. H2C2O4 ? 2CO2 + 2H+ + 2e- The two equations combine and are balanced to create the overall ionic equation. 2MnO4- + 6H+ + 5H2C2O4 ? 2Mn2+ + 8H2O + 10CO2 Equipment list: * Potassium permanganate (0.02moldm-3) * Mixture of oxalic acid and sulphuric acid * Conical flask * 25ml pipette * Pipette filler * Funnel * Burette * Retort stand * Clamp Method: 1) Use the pipette and the pipette filler to collect 25ml of the mixture of oxalic acid and sulphuric acid and put it in the conical flask.
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� Aldehydes and ketones may be toxic. � Silver metal poses little threat. � Ammonia in solution is particularly damaging to the eyes, besides being toxic if swallowed and harmful to the skin. � Wear goggles and gloves, avoid contact with chemicals. The Instructions: Tollen's reagent must be prepared within a couple of hours of use. Preparation instructions for testing one chemical: - Add a drop of dilute NaOH to 1cm3 of AgNO3. A brown precipitate (silver oxide) will form. - Add concentrated NH3 until the precipitate just dissolves. Add a few drops of the carbonyl compound to the prepared Tollen's reagent in a test tube.
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This produces dibromoalkane. The OH group on Phenol is electron releasing, because the oxygen p-orbital is delocalised, therefore the electron density of the delocalised ring is increased. It makes the substitution of Bromine with the Hydrogen atom much easier compared with, for example, Benzene. Substitution usually takes place at the 2, 4 and 6 positions. Using a pipette add 6 drops of the unknown compound to a test tube comprised of 25cm3 Bromine water. Then shake the test tube so that the compound and the bromine water are thoroughly mixed together.
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