AQA A level Chemistry Questions and Answer (updated) 2022 Grade A
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AQA A level Chemistry (AQA)
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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?{{{An...
aqa a level chemistry questions and answer updated 2022 grade a
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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)
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