Chemistry Paper 2 | OCR | Brian Peter | 2025 | Extensive Exam Revision Notes and Practice, Exams of Chemistry

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Chemistry Paper 2 OCR.

BRIAN PETER

CHEMISTRY

"how to calculate the formula of a hydrated salt? - CORRECT ANSWER 1. calculate the moles of the anhydrous salt

2. calculate the moles of water formed
3. find the smallest whole number ratio between anhydrous and water formed to calculate formula" "what are the assumptions made for the hydrated salt practical? - CORRECT ANSWER
4. all of the water has been lost
5. no further decomposition" "Standard solution - CORRECT ANSWER a solution of known concentration" "Molar gas volume - CORRECT ANSWER The volume per mole of gas molecules at a stated temperature and pressure" "equation for n in molar gas volume - CORRECT ANSWER n=volume/molar gas volume" "Molar gas volume at RTP - CORRECT ANSWER 24 dm³ / mol" "4 assumptions for the molecules making up an ideal gas - CORRECT ANSWER 1. random mutation
6. elastic collisions
7. Negligible size
8. No intermolecular" "what are the units for pV=nRT - CORRECT ANSWER p= pascals V= volume T= kelvin" "Stoichiometry - CORRECT ANSWER The calculation of quantities in chemical reactions" "Theoretical yield - CORRECT ANSWER the maximum amount of product that can be produced from a given amount of reactant" "Percentage yield - CORRECT ANSWER actual yield/theoretical yield x 100" "limiting reagent - CORRECT ANSWER the reactant that determines the amount of product that can be formed in a reaction" "Atom economy - CORRECT ANSWER (Molecular mass of desired products/ Molecular mass of all products) x 100" "strong acid - CORRECT ANSWER Releases all its hydrogen atoms into solution as H+ ions and completely dissociates in aq solution"

unable to polarize electrophiles so can't attract them strongly. In C=C of alkenes the Pi electrons are localised. Pi electron density is high (compared to benzene) able to polarize electrophiles so attracts them strongly." "which groups are electron donating on benzene? - CORRECT ANSWER OH and NH increase the electron density in the delocalised ring of pi electrons therefore they are more reactive towards electrophiles direct substitutions to positions 2 and 4 on benzene ring" "which group are electron donating on benzene? - CORRECT ANSWER NO decrease the electron density in the delocalised ring of pi electrons therefore they are less reactive towards electrophiles direct substitutions to position 3 on benzene ring" "how does an amine act as a base? - CORRECT ANSWER can accept H+ ions using lone pair on N (coordinate bond) forming an ammonium salt" "how is a primary aliphatic amine made? and why does the reagent need to be in excess - CORRECT ANSWER from reacting haloalkane with excess ammonia in ethanol. excess ammonia avoids further substitution to secondary and tertiary amines." "how is a secondary and primary amine made? - CORRECT ANSWER from reacting excess haloalkane with ammonia and ethanol the lone pair on the N of the primary amine will attack another haloalkane" "how is an aromatic amine made? - CORRECT ANSWER by reducing nitrobenzene using tin and concentrated HCl" "how are amines made from nitriles/hydroxynitriles? - CORRECT ANSWER by reducing nitriles using H2/Ni catalust" "how to test for an alkene? - CORRECT ANSWER react with Br2 and bromine is decolourised" "how to test for a carbonyl compound? - CORRECT ANSWER Add 2,4-DNP, orange precipitate forms with carbonyl compounds" "how to test for a haloalkane? - CORRECT ANSWER react with silver nitrate, nitric acid and ethanol -chloroalkane white ppt AgCl -bromoalkane cream ppt AgBr -iodoalkane yellow ppt"

"what is the test for a silver halide? - CORRECT ANSWER silver chloride dilute ammonia dissolves silver bromide conc ammonia dissolves silver iodide insoluble" "How to test for an aldehyde? - CORRECT ANSWER add tollen's reagent and heat positive result is a silver mirror" "how is a nitrile produced from a haloalkane? - CORRECT ANSWER CN- and ethanol" "how is a hydroxy nitrile formed? - CORRECT ANSWER by mixing CN- and sulfuric acid" "what are the reagents to produce an alkane --> haloalkane - CORRECT ANSWER halogen and UV light" "what are the reagents to produce an alkene --> haloalkane - CORRECT ANSWER hydrogen halide" "what are the reagents to produce an alkene --> alkane - CORRECT ANSWER H Nickel" "what are the reagents to produce an alcohol --> alkene - CORRECT ANSWER H3PO heat" "what are the reagents to produce an alkene --> alcohol - CORRECT ANSWER H2O (steam)/ H3PO4" "what are the reagents to produce an alcohol --> haloalkane - CORRECT ANSWER NaX H2SO4" "what are the reagents to produce a Haloalkane --> alcohol - CORRECT ANSWER NaOH (aq)" "what are the reagents to produce a haloalkane --> nitrile - CORRECT ANSWER CN-/ethanol" "what are the reagents to produce a haloalkane --> amine - CORRECT ANSWER NH ethanol" "what are the reagents to produce a nitrile --> Amine - CORRECT ANSWER H2/Ni" "what are the reagents to produce a hydroxy-nitrile --> amine - CORRECT ANSWER H2/Ni"

"what are the reagents to produce an acyl chloride --> Ester - CORRECT ANSWER alcohol" "what are the reagents to produce an ester --> carboxylate - CORRECT ANSWER OH- heat" "what are the reagents to produce an acyl chloride --> primary amide - CORRECT ANSWER NH3" "what are the reagents to produce an acyl chloride --> secondary amide - CORRECT ANSWER primary amine" "what are the reagents to produce a benzene --> nitrobenzene - CORRECT ANSWER cHNO3 and cH2SO4" "what are the reagents to produce a nitrobenzene --> phenylamine - CORRECT ANSWER Sn HCl" "what are the reagents to produce a phenyl amine to bromophenyl amine - CORRECT ANSWER Br2" "what are the reagents to produce a benzene --> methylbenzene - CORRECT ANSWER CH3Cl AlCl3" "what are the reagents to produce a benzene to bromo benzene - CORRECT ANSWER Br2 AlBr3" "what are the reagents to produce a benzene to chloro benzene - CORRECT ANSWER Cl2 AlCl3" "what are the reagents to produce a phenol -> bromo phenol - CORRECT ANSWER Br2" "what happens when phenol reacts with a strong base? - CORRECT ANSWER acts as an acid and produces a salt for example O-Na+" What two types of bond are within an alkene? - CORRECT ANSWER sigma and pi" "sigma bond - CORRECT ANSWER the direct overlapping of two orbitals" "pi bond - CORRECT ANSWER the sideways overlap of p orbitals" "C=C how many pi bonds and sigma bonds are in this - CORRECT ANSWER one sigma two pi bonds"

"what two types of isomers are found in alkenes - CORRECT ANSWER cis/trans and E/Z" "Difference between E/Z isomers and Cis/trans isomers - CORRECT ANSWER E/Z compares relative position based in priority groups (IP rules) look at the atomic number of the first bonded element Cis/Trans compares the relative positions of identical groups" "major and minor products in alkenes - CORRECT ANSWER the major product forms the most stable carbocation intermediate during alkene reactions tertiary>secondary>primary" "what type of polymer do alkenes produce? - CORRECT ANSWER addition polymers" "synthesis of an organic liquid - CORRECT ANSWER once reaction is complete into a separating funnel. Neutralise any excess acid using sodium carbonate (stops bubbling when all gone) Allow 2 layers to settle Use density into to establish layers. If density into not given, add water to establish aqueous layer. (aqueous layer get bigger) Density of water is 1 anything greater is more dense. collect the organic layer add a drying agent to remove small traces of water left in the organic layer (e.g.. anhydrous CaCl2) If the question tells you the boiling point of the organic liquid say distil dried product and collect fraction that comes over the boiling point." "3 ways to determine purity of products - CORRECT ANSWER 1. boiling point should match known data, boils over a narrow range or

2. Run TLC, measure Rf value, compare to known data values/Run TLC and compare to chromatogram of pure sample or
3. Run NMR/IR/Mass spectrum, compare to spectral database of pure compounds." "How to purify by recrystallisation? - CORRECT ANSWER -dissolve in a minimum volume of hot solvent -cool in ice to recrystallise (impurities stay in solution) -filter using Büchner flask/reduced pressure filtration -wash with cold solvent -dry" "Does reflux have an open or closed system? - CORRECT ANSWER open"

-the relative isotopic mass of each isotope." "What is the display formula for a dative covalent bond? - CORRECT ANSWER " "Electron pair repulsion theory - CORRECT ANSWER Electrons repel one another due to their like charges. This means that when bonded to molecules will be as far away as possible to one another, allowing us to determine the shapes of molecules" "A solid line shows - CORRECT ANSWER Represents a bond in the plane of the paper" "a solid wedge - CORRECT ANSWER represents a bond that projects out of the plane of the paper" "A dotted wedge represents - CORRECT ANSWER A bond that goes into the plane of the paper" "Lone pair repulsion - CORRECT ANSWER a lone pair of electrons is slightly closer to the central atom, and occupies more space, than a bonded pair. This results in a lone pair repelling more strongly than a bonding pair. increases the bond angle by 2.5" "describe the bonding and shape of CO2 - CORRECT ANSWER 2 bonding regions electron pairs repel each other bond angle of 180 degrees and linear shape" "describe the bonding and shape of SO4 2- - CORRECT ANSWER -four boning regions electrons pairs repeal each other bond angle of 109. degrees and tetrahedral shape" "describe the bonding and shape of CO3 2- - CORRECT ANSWER -3 bonding regions -electrons repel each other

• bond angle 120 degrees and trigonal planar shape" "draw SO4 2- - CORRECT ANSWER slay" "describe the bonding and shape of SF6 - CORRECT ANSWER -6 bonding regions -electron pairs repeal each other -bond angle is 90 degrees and shape is octahedral" "electronegativity - CORRECT ANSWER the attraction of a bonded atom for the pair of electrons in a covalent bond."

"most electronegative element - CORRECT ANSWER Fluorine" "3 of the most electronegative elements - CORRECT ANSWER oxygen fluorine and chlorine" "3 of the least electronegative elements - CORRECT ANSWER " "non polar bond - CORRECT ANSWER a covalent bond in which electrons are shared equally" "polar covalent bond - CORRECT ANSWER A covalent bond in which electrons are not shared equally" "three main categories of intermolecular forces - CORRECT ANSWER 1. induced dipole-dipole interactions

2. permanent dipole-dipole interactions
3. hydorgen bonding" "what type of intermolecular force has the greatest bond enthalpy? - CORRECT ANSWER hydrogen bonding" "what effect does an increase in electrons have on the strength of an induced dipole dipole - CORRECT ANSWER stronger/ larger induced dipole dipole." "Van der Waal forces - CORRECT ANSWER induced dipole-dipoles and permanent dipole dipoles" "London forces - CORRECT ANSWER induced dipole dipoles" "solubility of non-polar simple molecular substances in non polar solvent - CORRECT ANSWER intermolecular forces form between the molecules and the solvent. the interactions weaken the intermolecular forces in the simple molecular lattice. The intermolecular forces break and the compound dissolve" "solubility of non polar simple molecular substances in polar solvents - CORRECT ANSWER there is little interaction between the molecules in the lattice and solvent molecules. the intermolecular bonding within the polar solvent is too strong to be broken. Therefore they are insoluble." "Solubility of polar simple molecular substances - CORRECT ANSWER polar covalent substances may dissolve in polar solvents as the polar solute molecules and the polar solvent molecules can attract each other" "what elements form hydrogen bonds? - CORRECT ANSWER N, O, F"

"mechanism of an aldehyde/ketone to an alcohol - CORRECT ANSWER nucleophilic addition" "what produces the silver mirror in the tollens reagent? - CORRECT ANSWER Ag+ is reduced to Ag" "Are carboxylic acids strong or weak acids? - CORRECT ANSWER weak" "when carboxylic acts as an acid what is its product - CORRECT ANSWER a carboxylate ion which forms a part of the ion in the carboxylate salt" "how to calculate Rf value for thin layer chromatography? - CORRECT ANSWER distance travelled by spot/ distance travelled by solvent" "why do some solutes travel further un thin layer chromatography than others? - CORRECT ANSWER relative absorption of the solute to the solvent" "how is separation done in gas chromatography if the stationary phase is solid? - CORRECT ANSWER relative adsorption" "how is separation done in gas chromatography if the stationary phase is liquid? - CORRECT ANSWER relative solubility" "what is measured for gas chromatography? - CORRECT ANSWER retention times time from injection to detection compare retention times to known data values" "what does the area under peaks on a gas chromatogram tell you? - CORRECT ANSWER relative amounts of components in sample" "how is actual concentration found using gas chromatography? - CORRECT ANSWER by measuring area under curve for known concentration then plotting a calibration curve." "what do mass spectrometers measure? - CORRECT ANSWER mass to charge ratio (m/z)" "what must you not forget for writing mass spectrometer fragments? - CORRECT ANSWER the positive charge on your formulae" "where is the molecular ion peak on a mass spectrometer? - CORRECT ANSWER the peak furthest right (M+)"

"what creates fragment peaks on a mass spectrometer? - CORRECT ANSWER by breaking of one covalent bond in the molecular ion" "1kg into g - CORRECT ANSWER 1000g" "1mg into g - CORRECT ANSWER 0.001g" "where to find the conversion to from tonnes to grams? - CORRECT ANSWER on the formula sheet" "hyrdocarbon - CORRECT ANSWER compound containing only carbon and hydrocarbon" "saturated - CORRECT ANSWER contains only C-C single bonds" "unsaturated - CORRECT ANSWER C=C Ctriple bondC aromatic benzene ring" "aliphatic - CORRECT ANSWER straight chain, branched chain, non aromatic rings" "alicyclic - CORRECT ANSWER ring but not aromatic ring" "cyclic - CORRECT ANSWER any ring" "aromatic - CORRECT ANSWER Containing one or more benzene rings" "homologous series - CORRECT ANSWER A series of organic compounds with the same functional group but with each successive member differing by CH2" "functional group - CORRECT ANSWER the part of the organic molrcule that is largely responsible for the molecules chemical properties" "alkynes - CORRECT ANSWER contain at least one carbon-carbon triple bond" "in what order are prefix's listed? - CORRECT ANSWER alphabetical" "general formula for alkanes - CORRECT ANSWER CnH2n+2" "general formula for alkenes - CORRECT ANSWER CnH2n" "general formula for alcohols - CORRECT ANSWER CnH2n+1OH" "general formula for carboxylic acids - CORRECT ANSWER CnH2nO2" "general formula for ketones/aldehydes - CORRECT ANSWER CnH2nO"

"what are the 2 limitations of radical substitution in organic synthesis? - CORRECT ANSWER further substitution-the further reaction with another radical substitution at different position in a carbon chain" "optical isomers - CORRECT ANSWER structural isomers that are non-superimposable mirror images of each other" "what is the strongest pi bond and sigma bond? - CORRECT ANSWER sigma bond so pi bonds are broken more readily" "what is the catalyst needed for the hydrogenation of an alkene? - CORRECT ANSWER nickel" "what mechanism do alkenes react? - CORRECT ANSWER electrophilic addition" "carbocation - CORRECT ANSWER positive charge on a carbon atom" "what carbocation is the most stable? - CORRECT ANSWER tertiary" "what type of polymerisation do alkenes undergo? - CORRECT ANSWER addition polymerisation" "4 ways to dispose of waste polymers - CORRECT ANSWER recycling PVC recycling Feedstock recycling using waste polymers as fuels" "feedstock recycling - CORRECT ANSWER describes the chemical and thermal processes that can reclaim monomers, gases, or oil from waste polymers." "bioplastics - CORRECT ANSWER produced from plant starch, cellulose, plant oils and proteins offer a renewable and sustainable alternative to oil-based products" "two types of degradable polymers - CORRECT ANSWER biodegradable and photodegradable polymers" "difference between primary secondary and tertiary alcohols - CORRECT ANSWER primary alcohol is only has one carbon attached to the carbon attached to the OH- bond" "properties of alcohols - CORRECT ANSWER -have a higher boiling point than alkanes due to there OH group that forms hydrogen bonds -solubility in water due to the hydroxyl groups" "how many water molecules are produced when an alcohol is oxidised to aldehyde - CORRECT ANSWER one water molecule"

"how many water molecules are produced when an alcohol is oxidised to a carboxylic acid - CORRECT ANSWER one water molecule" "how many water molecules are produced when an aldehyde is oxidised to a carboxylic acid - CORRECT ANSWER none" "how many water molecules are produced when an alcohol is oxidised to a ketone - CORRECT ANSWER one water molecule" "products of a metal with a carboxylic acid - CORRECT ANSWER carboxylate salt and hydrogen" "products of a metal oxide with a carboxylic acid - CORRECT ANSWER carboxylate salt and water" "products of an alkali with a carboxylic acid - CORRECT ANSWER carboxylate salt and water" "what is the ionic equation for a reaction of a carboxylic acid and a alkali - CORRECT ANSWER H+ + OH- -> H2O" "what are the products of when a carboxylic acid reacts with a carbonate - CORRECT ANSWER carboxylate salt, water and carbon dioxide" "how to test for a carboxyl group - CORRECT ANSWER the neutralisation reaction of carboxylic acids with carbonates they are the only common organic compounds sufficiently acidic to react with carbonates. Especially useful for distinguishing carboxylic acids from phenol" "how to name an ester - CORRECT ANSWER the suffix is the chain which was the carboxylic acid and the prefix is the other chain (the alcohol)" "How to name an acyl chloride - CORRECT ANSWER remove the -oic acid suffix from the parent carboxylic acid and replace with -oyl chloride" "acid anhydride - CORRECT ANSWER Formed by the removal of water from two carboxylic acid molecules." "how to name an acid anhydride - CORRECT ANSWER replace acid with anhydride 2 ethanoic acid --> ethanoic anhydride" "what type of reaction is esterification? - CORRECT ANSWER condensation reaction as it produces water molecule" "acid hydrolysis of an ester

"aromatic amine - CORRECT ANSWER the nitrogen atom is attached an aromatic ring." "what is primary amine - CORRECT ANSWER R-NH2" "two examples amines - CORRECT ANSWER serotonin and pseudoephedrine" "how do amines act as a base? - CORRECT ANSWER lone pair of electrons on nitrogen that allows them to accept a proton to form ammonium ion" "what are the products when amine reacts with acid - CORRECT ANSWER ammonium salt" "general formula of amino acid - CORRECT ANSWER RCH(NH2)COOH" "what are the products when amino acid reacts with an aq alkali - CORRECT ANSWER carboxylate salt and water" "what are the products when an amino acid reacts with an acid - CORRECT ANSWER ammonium salt" "how can an amino acid be esterified? - CORRECT ANSWER heating with an alcohol in the presence of concentrated sulfuric acid" "what are the products when an amino acid is esterified with an alcohol in presence of a sulfuric acid concentrated - CORRECT ANSWER -ester with NH3+ and water" "How are amides formed? - CORRECT ANSWER Amides are formed by the condensation reaction of acyl chloride and ammonia or an amine." "how to name secondary amides - CORRECT ANSWER amine named first with its parent chain for example N-methyl carboxylic acid named second with its parent chain for example ethanamide" "enantiomers - CORRECT ANSWER optical isomers" "where are optical isomers found - CORRECT ANSWER found in molecules with chiral centres" "acid hydrolysis of an ester -reactants -products - CORRECT ANSWER H+ /H2O carboxylic acid and alcohol"

"base hydrolysis of an ester -reactants -products - CORRECT ANSWER NaOH/H2O alcohol and carboxylate salt" "acid hydrolysis of the polyamides -reactants -products - CORRECT ANSWER H+/H2O -ammonium ion and a carboxylic acid" "base hydrolysis of the polyamides -reactants -products - CORRECT ANSWER -NaOH/H2O -carboxylate salt and amine" "what is the purpose of deuterium oxide in proton NMR - CORRECT ANSWER deuterium exchanges and replaces the OH and NH protons in the sample with deuterium atoms because OH and NH are difficult to assign cause they have a broad peal" "what is the solvent in proton NMR spectroscopy - CORRECT ANSWER D2O" "what is the standard for proton NMR spectroscopy - CORRECT ANSWER TMS" ""how to work out relative atomic mass using isotope masses? - CORRECT ANSWER sum (percentage x mass number) all divided by 100" "What is the charge of a Ag cation? - CORRECT ANSWER +1" "what is the charge of a Zn cation? - CORRECT ANSWER 2+" "binary compound - CORRECT ANSWER only has two elements" "what is the cation for Al? - CORRECT ANSWER 3+" "how to calculate number of molecules in a specified mass of a compound? - CORRECT ANSWER n x Avogadro's constant" "empirical formula - CORRECT ANSWER the simplest whole-number ratio of atoms of each element"