Reactions of Alkenes & Alcohols (AQA GCSE Chemistry)
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What is the general formula for alkenes?
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What is the general formula for alkenes?
The general formula for alkenes is CnH2n.
What is the formula of pentene?
The formula of pentene is C5H10.
What is the functional group in alkenes?
The double carbon bond (C=C) is the functional group in alkenes.
How are alkenes named?
Alkenes are named using the same system as alkanes, with the suffix "-ene" instead of "-ane".
Give the name and structure of the first alkene.
The name and structure of the first alkene is ethene, CH2=CH2.
What is an alkene?
An alkene is a hydrocarbon compound containing at least one carbon-carbon double bond.
Explain the term double bond.
A double bond is a covalent bond formed by sharing two pairs of electrons between atoms.
Explain what is meant by a unsaturated compound.
An unsaturated compound contains two fewer hydrogen atoms than the alkane with the same number of carbon atoms.
What is the name of this compound?
The name of the compound is propene.
What is the displayed formula of ethene?
The displayed formula of ethene is:
What is the name of the alkene with the formula C4H8?
Butene is the name of the alkene with the formula C4H8?
What are the products of complete combustion of alkenes?
The products of complete combustion of alkenes are carbon dioxide and water.
What causes the smoky flame when alkenes burn?
The smoky flame when alkenes burn is caused by incomplete combustion producing soot (carbon).
True or False?
Alkenes always undergo complete combustion in air.
False.
Alkenes often undergo incomplete combustion in air due to their higher carbon to hydrogen ratio.
What are the possible products of incomplete combustion of alkenes?
The possible products of incomplete combustion of alkenes are carbon monoxide, water, and carbon (soot).
What is incomplete combustion?
Incomplete combustion is the reaction of a fuel with insufficient oxygen, producing carbon monoxide and/or carbon (soot) along with water.
True or False?
Higher alkenes are more likely to produce soot when burning.
True.
Higher alkenes are more likely to produce soot when burning.
State the symbol equation for the complete combustion of butene, C4H8.
The symbol equation for the complete combustion of butene is:
C4H8 + 6O2 → 4CO2 + 4H2O
What condition is necessary for complete combustion to occur?
For complete combustion to occur, there must be excess oxygen available.
Write the symbol equation for the incomplete combustion of butene, C4H8, to form carbon and water.
The equation for the incomplete combustion of butene to form carbon and water is:
C4H8 + 2O2 → 4C + 4H2O
Give the symbol equation for the incomplete combustion of propene, C3H6, to form carbon monoxide and water.
The equation for the incomplete combustion of butene to form carbon monoxide and water is:
C3H6 + 3O2 → 3CO + 3H2O
What type of reaction is the reaction between bromine and propene an example of?
The reaction between bromine and propene is an example of an addition reaction.
What is an addition reaction?
An addition reaction is a reaction in which atoms of a simple molecule add across the carbon-carbon double bond so that the double bond becomes a single carbon-carbon bond.
How many products are formed in an addition reaction?
In an addition reaction, only one product is formed
What is the colour change for the following reaction?
The colour change for the following reaction is orange to colourless.
What product is formed when alkenes undergo addition reactions with hydrogen?
When alkenes undergo addition reactions with hydrogen, an alkane is formed.
What product is formed when alkenes undergo addition reactions with steam?
When alkenes undergo addition reactions with steam, an alcohol is formed.
What name is given to the reaction between alkenes and steam?
The reaction between alkenes and steam is also called a hydration reaction.
True or False?
In the reaction between ethene and steam, ethanol is produced.
True.
In the reaction between ethene and steam, ethanol is produced.
True or False?
Halogenation of alkenes occurs readily at room temperature.
True.
Halogenation of alkenes occurs readily at room temperature.
How are alcohols named?
Alcohols are named using the same system as alkanes and alkenes, with the final 'e' being replaced with 'ol'.
Give the name and formula of the first alcohol.
The name and formula of the first alcohol is methanol, CH3OH.
What is the name of the following alcohol?
The name of the alcohol is butanol.
What is the name of the following alcohol?
The name of the alcohol is ethanol.
True or False?
The -OH group in alcohols is the same as the hydroxide ion.
False.
The -OH group in alcohols is not the same as the hydroxide ion (OH⁻).
What is the molecular formula for ethanol?
The molecular formula for ethanol is C2H5OH.
What are the conditions for fermentation to produce ethanol?
The conditions for fermentation to produce ethanol are a temperature between 15 and 35°C and the absence of oxygen.
What are the first four alcohols commonly used for?
The first four alcohols are commonly used as fuels.
Methanol and ethanol are also used extensively as solvents.
Complete the equation for the combustion of ethanol.
CH3CH2OH + ...O2 → ... CO2 + 3H2O
The completed balanced symbol equation for the combustion of ethanol is:
CH3CH2OH + 3O2 → 2CO2 + 3H2O
What gas is formed when methanol reacts with sodium?
Hydrogen gas is formed when methanol reacts with sodium.
What type of compound is formed when an alcohol reacts with an oxidising agent?
A carboxylic acid is formed when alcohols react with an oxidising agent.
What is the molecular formula of ethanoic acid?
The molecular formula of ethanoic acid is CH3COOH.
What is the name of the following carboxylic acid?
The name of the following carboxylic acid is propanoic acid.
What is the functional group of carboxylic acids?
The functional group of carboxylic acids is -COOH.
What is produced when carboxylic acids react with metal carbonates?
When carboxylic acids react with metal carbonates, a salt, water, and carbon dioxide gas are produced.
What products are formed when magnesium carbonate and ethanoic acid react?
When ethanoic acid and magnesium carbonate react they form magnesium ethanoate, water and carbon dioxide.
How would you test for the gas produced when a carboxylic acid reacts with a metal carbonate?
To test for the gas produced when a carboxylic acid reacts with a metal carbonate:
Bubble the gas through limewater
If the limewater turns cloudy, carbon dioxide is present.
What type of compound is ethyl ethanoate?
Ethyl ethanoate is an ester.
What is the name of the following compound?
The name of the following compound is ethyl ethanoate.
What happens when carboxylic acids dissolve in water?
Carboxylic acids dissolve in water to form acidic solutions with pH values less than 7.
Are carboxylic acids strong or weak acids?
(Higher tier only)
Carboxylic acids are weak acids.
True or False?
Carboxylic acids fully ionise in water. (Higher tier only)
False.
Carboxylic acids only partially ionise in water.
Complete the equation to show the ionisation of propanoic acid.
CH3CH2OOH ... . H+ + CH3CH2COO–
(Higher tier only)
The completed equation for the ionisation of propanoic acid.
CH3CH2OOH ⇌ H+ + CH3CH2COO–
True or False?
The strength of an acid is related to its degree of ionisation in water. (Higher tier only)
True.
The strength of an acid is related to its degree of ionisation in water.
True or False.
The pH of a weak acid will be higher than the pH of a strong acid, if their concentrations are the same. (Higher tier only)
True.
The pH of a weak acid will be higher than the pH of a strong acid, if their concentrations are the same.
Is the ionisation of a carboxylic acid a reversible or irreversible reaction? (Higher tier only)
The ionisation of a carboxylic acid is a reversible reaction.
