AQA A level Chemistry Questions and Answer (updated) 2022 Grade A

AQA A level Chemistry Questions and Answer (updated) 2022 Grade A Question:-What's the Test for a Carbonyl group? {{{Answer}}} (Brady's reagent (2,4 DNPH) Orange to yellow precipitate) Question:-Do Carbonyls have a lower or higher boiling point when compared to a corresponding Alcohol?{{{Answer}}} (Lower) Question:-Do Carbonyls have a higher or lower boiling point when compared to a corresponding Alkane?{{{Answer}}} (Higher) Question:-Do Carbonyls dissolve in water?{{{Answer}}} (Yes limited association with water molecules) Question:-What's the test for an Aldehyde?{ {{Answer}}} (Tollens reagent - Silver mirror test OR Fehling's/Benedict's reagent blue to brick red) Question:-What is the Test for a Ketone? {{{Answer}}} (Negative result with an oxidizing agent like Fehlings) Question:-What is the Test for a Carboxylic Acid? {{{Answer}}} (Add a carbonate - CO2 formed and effervesence OR Universal indicator - red colour) Question:-Will a Carboxylic Test positive as a Carbonyl? {{{Answer}}} (No) Question:-What is the Oxidising Agent for Alcohols? {{{Answer}}} (Acidified Potassium Dichromate (K2Cr2O7)) Question:-Oxidising Agents to change Aldehydes to Carboxylics? {{{Answer}}} (Fehlings, Acidified Potassium Dichromate, Tollens) Question:-What is the Reducing agent for Carboxylics and Carbonyls? {{{Answer}}} (NaBrH4 OR LiAlH4) Question:-Can all Alcohols be Oxidized to a Carbonyl? {{{Answer}}} (Not Tertiary) Question:-Product of Oxiding a Primary Alcohol? {{{Answer}}} (Aldehyde, Carboxylic) Question:-Product of Oxidising a Secondary Alcohol? {{{Answer}}} (Ketone) Question:-Product of Oxidising a Ketone {{{Answer}}} (Not going to happen) Question:-What is the specific functional group determining a Carbonyl?{{{Answer}}} (C=O group) Question:-What is the reaction mechanism associated most associated with Carbonyls? {{{Answer}}} (Nucleophilic Addition) Question:-What are the conditions required for a Carbonyl to undergo Nucleophilic Addition with a cyanide ion? {{{Answer}}} (Hydrogen Cyanide, Potassium Cyanide Catalyst (Don't even think about doing it in the lab)) Question:-Asymmetrical Carbonyls will react with Nucleophiles to give products......Why is the product not optically active?{{{Answer}}} (Racemate....equal quantity of both Optical isomers) Question:-Asymmetrical alcohols will undergo Nucleophilic Substitution........Why is the product not optically active?{{{Answer}}} (Only one Optical isomer is produced) Question:-What is the reagent in the electrophilic addition of water to an alkene? {{{Answer}}} (Water with strong acid (sulfuric or phosphoric acid)) Question:-What two species are added to the carbons either side of the double bond when water is electrophilically added to an alkene?{{{Answer}}} (H and OH) Question:-What is the product when water is electrophilically added to an alkene? {{{Answer}}} (An alcohol) Question:-What is the general formula of an alcohol with no carbon rings? {{{Answer}}} (CnH2n+1OH) Question:-Where is the OH attached in aromatic alcohols?{{{Answer}}} (Directly to the ring) Question:-What are aromatic alcohols known as?{{{Answer}}} (Phenols) Question:-What is a primary alcohol? {{{Answer}}} (One which is attached to a carbon which is attached to 1 other carbon) Question:-What is a secondary alcohol? {{{Answer}}} (One which is attached to a carbon which is attached to 2 other carbons) Question:-What is a tertiary alcohol? {{{Answer}}} (One which is attached to a carbon which is attached to 3 other carbons) Question:-What is the C-O-H angle in an alcohol and why? {{{Answer}}} (~105° because the oxygen has two lone pairs which makes the functional group a V-shaped molecule) Question:-Why do alcohols have a much higher boiling point than alkanes with a similar molecular mass?{{{Answer}}} (Because they can form hydrogen bonds, which are not present in alkanes) Question:-Why do the boiling points of alcohols increase as chain length increases? {{{Answer}}} (Increased chain length leads to an increase in van der waals' forces) Question:-Why do the boiling points of alcohols decrease as branching increases? {{{Answer}}} (Because this weakens their van der waals' forces) Question:-Which types of alcohols are soluble in water and why? {{{Answer}}} (Those with short hydrocarbon chains because this allows the hydrogen bonding from the alcohol group to water molecules to dominate) Question:-Why aren't alcohols with long hydrocarbon chains soluble in water? {{{Answer}}} (Because unlike in short chain hydrocarbons the long, non-polar hydrocarbon chain dominates over the hydrogen bonding) Question:-What is the reagent in the dehydration of an alcohol? {{{Answer}}} (Concentrated sulfuric/phosphoric acid) Question:-What are the conditions of the dehydration of an alcohol? {{{Answer}}} (Reflux at 180°C) Question:-What is the product of the dehydration of an alcohol? {{{Answer}}} (Alkene) Question:-What is an alternative method to reflux with strong acid to dehydrate an alcohol? {{{Answer}}} (Pass vapour over a heated alumina (aluminium oxide) catalyst) Question:-Why can some alcohols not be dehydrated? {{{Answer}}} (Lack of an adjacent hydrocarbon) Question:-What is oxidation of alcohols used to differentiate between? {{{Answer}}} (Primary, secondary or tertiary alcohols) Question:-What is the usual reagent in the oxidation of alcohols? {{{Answer}}} (Acidified potassium (VI) dichromate) Question:-What are primary alcohols oxidised to? {{{Answer}}} (Easily to aldehydes, and then carboxylic acids) Question:-What are secondary alcohols oxidised to? {{{Answer}}} (Easily to ketones) Question:-What are tertiary alcohols oxidised to? {{{Answer}}} (Not oxidised under normal conditions, only break down under very vigorous oxidation) Question:-What is potassium dichromate usually oxidised with? {{{Answer}}} (Dilute sulfuric acid) Question:-What is it essential to do when making aldehydes from alcohols? {{{Answer}}} (Distill off the aldehyde before it is further oxidised to a carboxylic acid) Question:-What colour change do primary or secondary alcohols cause in potassium dichromate?{{{Answer}}} (Orange to green) Question:-What colour change do tertiary alcohols cause in potassium dichromate?{{{Answer}}} (None) Question:-What change in apparatus must be made to produce carboxylic acids instead of aldehydes? {{{Answer}}} (The Liebig condenser must be placed directly above the pear-shaped flask instead of to the side, so that any distilled aldehyde returns to the flask for further oxidation) Question:-What is the composition of methylated spirits? {{{Answer}}} (Ethanol, along with a small amount of poisonous methanol and a purple dye) Question:-What is an elimination reaction? {{{Answer}}} (One in which a small molecule leaves the parent molecule) Question:-What smell do most aldehydes and ketones have? {{{Answer}}} (A pleasant one) Question:-Are the physical properties of aldehydes and ketones similar? {{{Answer}}} (Yes) Question:-What 3 reactions suggest that burning ethanol is carbon neutral and why? {{{Answer}}} (Photosynthesis, fermentation and combustion of ethanol, because overall 6 carbon dioxides go in and 6 carbon dioxides come out) Question:-What is ethanol used as? {{{Answer}}} (A biofuel or as a solvent) Question:-What are 2 ways of producing ethanol? {{{Answer}}} (Hydration of ethene or fermentation of glucose) Question:-What are the reaction conditions of the hydration of ethene to make ethanol? {{{Answer}}} (Concentrated phosphoric acid catalyst, 300°C, 60 atm) Question:-How is over 90% of ethanol made?{{{Answer}}} (Fermentation using yeast) Question:-How is ethanol made using yeast? {{{Answer}}} (The yeast produces ethanol during anaerobic respiration, using glucose as its food) Question:-What is used as a source of glucose in fermentation? {{{Answer}}} (Carbohydrates such as sugar cane, sugar beet, rice and maize) Question:-What is the conditions of the fermentation of glucose? {{{Answer}}} (Yeast, 35°C, aqueous, anaerobic conditions) Question:-Why does the fermentation of glucose stop after the solution reaches around 15% ethanol concentration?{{{Answer}}} (Because at this concentration the enzymes in the yeast are denatured) Question:-Why must fermentation occur under anaerobic conditions? {{{Answer}}} (So that the ethanol produced is not then oxidised to ethanoic acid) Question:-How is ethanol removed from the aqueous mixture produced after fermentation? {{{Answer}}} (Distillation, as the boiling point of ethanol (78°C) is below that of water) Question:-Despite the equations suggesting so, why is ethanol not a true carbon-neutral fuel? {{{Answer}}} (Other processes such as fuel for machinery and transport) Question:-What is a growing concern about biofuels? {{{Answer}}} (Too much land is being used to make biofuels rather than to grow food) Question:-What is a biofuel? {{{Answer}}} (A renewable fuel made from plants) Question:-What is an alkene?{{{Answer}}} (An unsaturated hydrocarbon) Question:-What is an unsaturated hydrocarbon? {{{Answer}}} (A compound containing only carbon and hydrogen atoms and containing at least one carbon carbon double bond) Question:-What are van der Waals forces? {{{Answer}}} (Relatively weak intermolecular forces caused by temporary dipole dipole interaction) Question:-What is the general formula for an alkene? {{Answer}}} (CnH2n) Question:-How would you name an alkene given its displayed formula? {{{Answer}}} (Identify the longest carbon chain Identify the position of the carbon carbon double bond Identify any side chains) Question:-What are structural isomers? {{{Answer}}} (Molecules with the same molecular formula, but with different a structural formula) Question:-What are stereoisomers? {{{Answer}}} (Molecules with the same molecular AND structural formula but a different 3D arrangement of their atoms in space) Question:-What is E-Z isomerism? {{{Answer}}} (The highest priority groups are on the same side of the double bond) Question:-Describe the C=C double bond {{{Answer}}} (Double covalent bond Planar bond Area of high electron density) Question:-How do you assign the highest priority of groups in E-Z isomerism? {{{Answer}}} (The highest atomic number closest to the double bond has the highest priority If two groups have e.g. Only carbon and hydrogen, then the one with the most carbon atoms is assigned the highest priority)