The three homologous series, their functional groups and general formulae, the bromine water test, fermentation, and the reactions of each family. Chemistry only content.
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1.What is an alkene?
An unsaturated hydrocarbon containing a carbon to carbon double bond.
2.State the general formula for alkenes.
CnH2n
3.What is the functional group of an alkene?
The carbon to carbon double bond, C=C.
4.Name the first four alkenes.
Ethene, propene, butene and pentene.
5.Give the formula of ethene.
C2H4
6.Why are alkenes described as unsaturated?
The double bond means the molecule does not contain the maximum possible number of hydrogen atoms.
7.How do you test for an alkene?
Add bromine water. It changes from orange to colourless.
8.What happens when an alkene reacts with hydrogen?
The double bond opens and a hydrogen atom adds to each carbon, forming the corresponding alkane.
9.What happens when an alkene reacts with steam?
An alcohol is formed, as water adds across the double bond.
10.Which alcohol is formed from ethene and steam?
Ethanol.
11.Why are alkene reactions called addition reactions?
The double bond opens and atoms add on, so there is only one product and nothing is removed.
12.What is the functional group of an alcohol?
The OH group.
13.Name the first four alcohols.
Methanol, ethanol, propanol and butanol.
14.Give the formula of ethanol.
C2H5OH
15.What happens when an alcohol dissolves in water?
It forms a neutral solution.
16.What is produced when an alcohol reacts with sodium?
Hydrogen gas is given off.
17.What is produced when an alcohol burns?
Carbon dioxide and water.
18.What happens when an alcohol is oxidised?
A carboxylic acid is formed. Ethanol oxidises to ethanoic acid.
19.How is ethanol produced by fermentation?
Sugar solution is mixed with yeast and kept warm in the absence of oxygen, and the yeast converts the sugar into ethanol and carbon dioxide.
20.What conditions are needed for fermentation?
A temperature of around 25 to 35 degrees Celsius, aqueous conditions, yeast, and no oxygen.
21.Give three uses of alcohols.
As fuels, as solvents, and ethanol is the alcohol in alcoholic drinks.
22.What is the functional group of a carboxylic acid?
The COOH group.
23.Name the first four carboxylic acids.
Methanoic, ethanoic, propanoic and butanoic acid.
24.What is produced when a carboxylic acid reacts with a carbonate?
A salt, water and carbon dioxide.
25.Why are carboxylic acids described as weak acids?
They only partially ionise in water, so they produce fewer hydrogen ions than a strong acid of the same concentration.
26.How does the pH of a carboxylic acid compare with a strong acid?
It is higher, because fewer hydrogen ions are released.
27.What is vinegar?
A dilute solution of ethanoic acid.
28.Why do members of a homologous series react in similar ways?
They all contain the same functional group, which is the part of the molecule that determines the chemistry.
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