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Chemistry A2 f324
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- 1Define an electrophilean atom that accepts a pair of electrons
- 2What are the reagents and conditions required for nitration of benzene?concentrated HNO3 and H2SO4 catalyst, 50 degrees temperature
- 3Why is nitration of benzene carried out at 50 degrees?A higher temperature may lead to more than one nitro group being substituted
- 4Name a suitable halogen carrier for halogenation of benzeneAl Br3 or Fe Cl3
- 5Write two equations to show H2SO4 as a catalyst in nitration of benzeneHNO3+H2SO4 > NO2+ + HSO4- + H2O
- 6What kind of reaction is nitration of benzene?Electrophilic Substitution
- 7Write two equations to show AlBr3 as a catalyst in halogenation of benzeneAlBr3+Br2 > AlBr4- + Br+
AlBr4-+H >AlBr3 + HBr - 8Why does bromine readily react with cyclohexene and not benzene?In cyclohexene the electrons are localised across the double bond and have a high enough density to induce a dipole in bromine, whereas in benzene the electrons are delocalised and cannot induce a dipole, hence the need for a halogen carrier.
- 9When bromine is added to cyclohexene what would you see?Decolourisation of bromine water
- 10What is the organic product called when sodium hydroxide is added to phenol?Sodium phenoxide
- 11What organic product is formed from the reaction of phenol with bromine?2,4,6 - tribromophenol
- 12Why does phenol react readily with bromine?The lone pair on the oxygen atom is drawn into the benzene ring increasing electron density which is capable of inducing a dipole in bromine.
- 13Name some uses of phenolmaking dyes, making pharmaceuticals, detergents
- 14What is the reducing agent used to reduce ketones and aldehydes to alcohol?NaBH4
- 15What symbol is used in equations to represent the reducing agent?(H)
- 16What kind of reaction is the reduction of ketones and aldehydes?Nucleophilic addition
- 17Define a nucleophileAn atom that donates a pair of electrons to form a new covalent bond
- 18What is the systematic name for Bradys reagent?2,4-dinitrophenylhydrazine
- 19If an orange precipitate forms upon addition of Bradys reaction what must be present in the solution?A ketone or aldehyde
- 20How can you distinguish between a ketone and aldehyde?Add Tollen's reagent and if a silver mirror forms it is an aldehyde
- 21How can you make Tollens reagent?Add silver nitrate to sodium hydroxide, then add ammonia until the precipitate just dissolves
- 22Is Tollens a reducing or oxidising agent?Oxidising
- 23How can you identify a carbonyl compound?Purify the product through recrystallisation and measure the melting point which can be compared to a table of known values
- 24Define hydrolysisA reaction with water or hydroxide ions that breaks a chemical compound into two chemical compounds
- 25What is the advantage of using acid anhydrides and alcohol to form an ester instead of an alcohol and carboxylic acid?better yield and no need for a catalyst
- 26What are the products formed in acid hydrolysis of an esterAlcohol and carboxylic acid
- 27What is the catalyst in acid hydrolysis of an esterdilute HCl
- 28What are the products formed during alkaline hydrolysis of an estera salt and alcohol
- 29What are the meanings of each symbol in the short hand notation for a fatty acid X:Y (N)X = number of carbons
Y = number of double bonds (C=C)
N = position of double bonds - 30What is the structure of glycerol?CH2(OH)CH(OH)CH2(OH)
- 31Which stereoisomer of fatty acids can pack closer together?Trans as the structure is more linear
- 32What are the functions of HDLs?High density lipoproteins which transport cholesterol out of the blood and eventually out of the body
- 33What are LDLs?These are low density lipo-proteins which transfer lipids onto artery walls and build up fatty deposits
- 34How do you make biodiesel?Transesterification - react a triglyceride with methanol in the presence of NaOH catalyst
- 35What is a primary amine?An amine with only one carbon chain attached to the nitrogen atom
- 36Why are amines defined as weak bases?Each has a lone pair on the nitrogen atom which can accept a proton
- 37How can aliphatic amine be prepared?react halogenalkanes with an excess of ammonia using ethanol as the solvent
- 38What kind of reaction is the preparation of primary amines?Nucleophilic substitution
- 39Why is excess ammonia used in the preparation of primary amines?To minimise the chance of further substitution occurring
- 40How can aromatic amines be prepared?Use tin catalyst and concentrated HCl , heated under reflux followed by neutralisation of excess acid
- 41What products are formed from the reaction of nitrobenzene with HCl in presence of tin?Phenylamine and water
- 42What is diazotisation?Forming a diazonium ion when a mixture of phenylamine and nitrous acid is kept below 10 degrees
- 43How is nitrous acid produced during preparation of the diazonium ion?React together sodium nitrite and HCl:
NaNO2+HCl>HNO2+NaCl - 44What is a coupling reaction?When the diazonium ion ion is reacted with a phenol under ALKALINE conditions...the two benzene rings are linked together through the azo group -N=N-, usually on the carbon at position 4 of the phenol if it is free
- 45Define a peptideA compound made of amino acids linked by peptide bonds
- 46Define an alpha amino acidAn amino acid that has both a basic group and acidic group attached to the carbon
- 47What is the general formula of an amino acidRCH(NH2)COOH
- 48define a zwitterionA dipolar form of an amino acid that is formed from the donation of a hydrogen ion from the carboxyl group to the amino group...no overall charge as both charges are present
- 49Define isoelectric pointthe pH value at which the amino acid exists as a zwitterion
- 50What is amphotericcan react with both acids and bases
- 51What happens to an amino acid when the pH is more alkaline than the isoelectric point?It becomes negatively charged as the amino group loses a proton into solution
- 52What happens if the pH is more acidic than the isoelectric point?The amino acid becomes positively charged as the carboxyl group accepts a proton from the solution
- 53Define a condensation reactionTwo small molecules react together to form a larger molecule with the elimination of water
- 54Which products are formed from the acidic hydrolysis of a dipeptide?Two positively charged amino acids due to the presence of H+ ions in the acid
- 55What are the reagents and conditions for acidic hydrolysis of polypeptides?6MHCl under reflux for 24 hours, water
- 56What products are formed from alkaline hydrolysis of a polypeptide?Sodium salts
- 57What conditions and reagents are required for alkaline hydrolysis of polypeptides?100 degrees and NaOH
- 58Define a chiral carbonA carbon which has four different groups attached
- 59Define optical isomerismStereoisomers that are non superimposable mirror images of each other
- 60What is the main difference between the different enantiomers?Rotate plane polarised light in different directions
- 61What is a mixture containing both enantiomers called?A racemic mixture
- 62What kind of monomers does condensation polymerisation require?Monomers with two different functional groups
- 63What is the link called in polyesters?Ester linkage
- 64Which two kind of monomers can be used to form polyesters?A monomer with an alcohol group and carboxylic group or a dioic acid and a di-ol
- 65How many waters are produced from n monomers during polymerisation?2n-1
- 66Define a biodegradable polymerA polymer that breaks down completely into carbon dioxide and water
- 67Define a degradable polymerA polymer that breaks down into smaller fragments when exposed to light, heat or moisture
- 68What are the products from acidic hydrolysis of a polyamidethe dicarboxylic acid and ammonium salt of diamine
- 69What are the products from alkaline hydrolysis of polyamides?The sodium salt of dicarboxylic acid and the diamine
- 70What are photodegradable polymers?Synthetic polymers which become weak when exposed to sunlight for a long period of time
- 71Define pharmacological activitythe beneficial or adverse effects of a drug on living matter
- 72name some disadvantages of using a racemic mixture in a drugHarmful side effects could be caused by the unwanted optical isomer, double the dose is required and increased cost
- 73How can you separate a racemic mixture?use of enzymes, electrophoresis or chromatography
- 74How can you prepare a single isomer?Use enzyme as biological catalysts, chiral pool synthesis and use of transition metal complexes.
- 75Define mobile phaseThe phase that moves in chromatography
- 76Define stationary phaseThe phase that does not move in chomatography
- 77How does a solid stationary phase separate components?Adsorption
- 78How does a liquid stationary phase separate components?By relative solubility
- 79What is the stationary phase in tlc?Silica gel
- 80define a chromatogramA visible record showing the result of separation of the components of a mixture by chromatography
- 81how do you calculate the Rf value?(distance moved by component)/(distance moved by solvent)
- 82What are some limitations of tlc?many compounds have similar Rf values and some have unknown values. Difficult to find a suitable solvent
- 83Describe how gas chromatography worksMixture is vaporised in the chromatograph, the mobile carrier flushes the mixture through the column and the components slow down as they interact with the stationary phase resulting in different retention times
- 84define retention timethe time for a component to pass from the column inlet to the detector
- 85Give some uses for GC-MSForensic science, environmental analysis, airport security and space probes
- 86Define chemical shifta scale that compares the frequency of an NMR absorption with the frequency of the reference peak
- 87What is TMS?The reference peak...tetramethylsilane
- 88Why is TMS used?It has twelve equivalent protons and so leads to one single sharp peak
- 89what kind of solvents are used for NMR analysis?Deuterated solvents like CDCl3
- 90What can a carbon NMR spectrum tell us?the number of environments and the type of carbon environment
- 91What can a proton NMR tell us?the number of environment, relative proton numbers in that environment, type of environment and number of protons attached to adjacent carbon
- 92how many adjacent protons are next to the protons causing a triplet?2 non equivalent protons
- 93how can you identify a OH or NH peak?Add D2O and the peak produced due to these protons will disappear
- 94What is the equation for the addition of D2O to ethanol?CH3CH2OH+D2O > CH3CH2OD + HOD
- 95Give some uses of NMRMRI scans, body scanning - sports injuries
- 96What are some advantages of using NMR in medicine?Non - invasive, harmless, low energy radiation
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- Fichas sobre Chemistry A2 f324, creado por nicola.bowen el 16/05/2014.
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