Alcohols & Carboxylic Acids (Edexcel GCSE Chemistry)

Exam Questions

3 hours20 questions
1a1 mark

Ethanol is produced by fermentation.

Which of the following conditions is not required to produce ethanol by fermentation?

  A A temperature of between 15 oC and 35 oC
  B The addition of yeast
  C The presence of oxygen
  D Sugar or starch dissolved in water
1b3 marks

During the process of fermentation two products are formed.

i)
Write the word equation for the process of fermentation.
(1)
ii)
Describe a chemical test for the gaseous product formed.
(2)
1c1 mark

What process is used to purify the ethanol produced by fermentation?

1d2 marks

Complete the displayed formula of ethanol shown in Figure 1.

9-4-1d-e-incomplete-ethanol-displayed-formula-a

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2a1 mark

Methanol and ethanol are both members of the same homologous series.

Which of the following is the functional group of this homologous series?
  A C=C
  B –COOH
  C –OH
  D C–C
2b1 mark

Which of the following is not a feature of a homologous series?

  A the compounds differ by CHin molecular formula from neighbouring compounds
  B they have similar chemical properties
  C they have the same general formula
  D they have the same physical properties
2c2 marks

Ethanoic acid can be produced from ethanol.

Use words from the box to complete the sentences about ethanol and ethanoic acid.

         –OH oxidised           –COOH heated
  reduced C=C neutralised decomposed



Ethanol can be ............................... to form ethanoic acid.

The functional group of ethanoic acid is ....................................... .

2d2 marks

Like ethanoic acid, propanoic acid is a carboxylic acid.

Draw the structure of propanoic acid. You should show all of the bonds in the structure.

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3a1 mark

Alcohols are a homologous series with the functional group -OH. 

Name the alcohol that has three carbon atoms. 

3b1 mark

Propanol can be oxidised to produce a carboxylic acid. 

Which carboxylic acid will be produced?

  A Ethanoic acid
  B Propanoic acid
  C Butanoic acid
  D Pentanoic acid
3c2 marks

Explain why propanol can not be referred to as a hydrocarbon.

3d3 marks

Ethanol is made by a process called fermentation.

Use the words in the box to complete the sentences on fermentation.

cool energy yeast warm
high oxygen carbon dioxide

During fermentation, sugar is converted to ethanol by adding ___________________. 

The reaction takes place at a ____________________ temperature in the absence of _____________________. 

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4a1 mark

This question is about carboxylic acids.

The structure of a carboxylic acid is shown in Figure 1. 

 
aqa-gcse-7-2e-tq3a-ethanoic-acid
Figure 1

Name the carboxylic acid shown in Figure 1. 

4b1 mark

Carboxylic acids can be formed from alcohols.

Which type of reaction takes place during this process?

  A Combustion
  B Oxidation
  C Decomposition
  D Neutralisation
4c1 mark

The carboxylic acid, propanoic acid, will react with sodium carbonate in a neutralisation reaction to produce sodium ethanoate and two other products. 

Which two other products will form?

  A water and hydrogen
  B water and carbon dioxide
  C carbon dioxide and hydrogen
  D carbon dioxide and sodium

4d2 marks

Higher Only

Ethanoic acid is a weak acid. 

Here are five statements about weak acids. 

Place ticks in the boxes by the two statements that are correct.

 weak acids fully ionise in solution  
 weak acids form solutions with a pH of 1  
 weak acids have a lower concentration of hydrogen ions compared to strong acids  
 weak acids partially ionise in solution  
weak acids release OH- ions  

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5a2 marks

This question is about alcohols. 

Figure 1 shows an incomplete diagram of the structure of a molecule of butanol, CH3CH2CH2CH2OH. 

Complete the structure of the molecule of butanol. 

q4a--butanol-structure

Figure 1

5b1 mark

A student used an alcohol burner to find the mass of different alcohols needed to raise the temperature of 100 cm3 of water by 20 oC. 

Figure 2 shows their results. 

alcohol initial mass of alcohol burner and alcohol in g final mass of alcohol burner and alcohol in g  mass of alcohol used in g 
ethanol 123.61 123.12 0.49
propanol 167.54 167.12 0.42
butanol 153.52 153.13  
pentanol 66.32 65.86 0.46

Figure 2

5c1 mark

Name the piece of equipment that could be used to measure the temperature increase of the alcohol. 

5d2 marks

The results show that 0.46 g of pentanol was needed to raise the temperature of the water by 20oC. 

Calculate the mass of pentanol needed to raise the temperature of water by 1oC. 

Give your answer to 2 decimal places. 

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1a1 mark

Alcohols and carboxylic acids are important organic compounds.

Figure 8 shows the names and formulae of three alcohols in a homologous series.

name formula
methanol CH3OH
ethanol C2H5OH
propanol C3H7OH

Figure 8   

Predict the formula of the alcohol that has five carbon atoms in its molecule, using the information in Figure 8.

1b
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2 marks

Calculate the relative formula mass of ethanol, C2H5OH.

(relative atomic masses: H = 1, C = 12, O = 16)

relative formula mass = ..............................................................

1c2 marks

Ethanol can be oxidised to form ethanoic acid.

Draw the structure of a molecule of ethanoic acid, showing all the covalent bonds.

1d4 marks

The temperature rise in water when liquid fuels burn can be found using the equipment shown in Figure 9.

fig-9-q6d-1cho-2f-specimen-2018

Figure 9

i)

A student compares the temperature rise produced in the water when
propanol burns with the temperature rise produced when ethanol burns.

State two factors that the student must keep the same in both experiments in order to have a fair comparison.

(2)

ii)
The results for the two alcohols are shown in Figure 10.

alcohol

mass of alcohol burned / g

temperature rise / °C
ethanol 0.33 20
propanol 0.28 20

Figure 10

Explain, using only the information in Figure 10, why propanol might be the better fuel.

(2)

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21 mark

What is the reading on the following thermometer?

7-1-q10-ocr-gcse-chemistry-mcq

  A 28.3 oC
  B 28.6 oC
  C 29.2 oC
  D 28.5 oC

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3a
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5 marks

Ethanol can be used as a liquid fuel.

A student investigates how much heat energy is released when a known mass of ethanol is burned.

The apparatus is set up as shown in Figure 15.

A known volume of water is placed in a metal can.
The temperature of the water is measured.
The ethanol is ignited and placed under the beaker so that the flame is touching the beaker.
The water is heated by the flame.
The flame is extinguished.
The final temperature of the water is measured.

fig-15-q10-1cho-2f-paper-1-june-2018

Figure 15

The theoretical temperature rise for burning a given mass of ethanol is 82.4 °C.

In the experiment the actual temperature rise for burning this mass of ethanol was only 34.8 °C.
One reason why the temperature rise is less than expected is that the ethanol does not burn completely.

i)
Give a reason why, even if the ethanol burns completely, the actual temperature rise is much less than the theoretical value.
(1)
ii)
Explain how the method described above could be improved to give a temperature rise closer to the theoretical value.
(2)
iii)
The amount of heat energy used to raise the temperature of the water by 34.8 °C can be calculated using

heat energy = 210 × temperature rise

Calculate the amount of heat energy used.

(2)

heat energy = ........................ (energy units)

3b3 marks

Propanol and butanol are both members of the same homologous series as ethanol.

fig-q10b-1cho-2f-paper-1-june-2018

Propanol and butanol can also be burned in the apparatus shown in Figure 15.

Give three reasons why ethanol, propanol and butanol are members of the same homologous series.

reason 1 ..............................................

reason 2 ..............................................

reason 3 .............................................

3c3 marks

Ethanol can oxidise when exposed to air to produce ethanoic acid and water.
Propanol can also oxidise in a similar reaction when it is exposed to air.

i)
Write the word equation for the reaction when propanol oxidises when it is exposed to air.
(2)
ii)
What is the formula of the functional group in carboxylic acids?
(1)
  A -OH
  B -CH3
  C -COOH
  D -CO2

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41 mark

Ethanol is produced by fermentation.

Which of the following conditions is not required to produce ethanol by fermentation?

  A A temperature of between 15 oC and 35 oC
  B The addition of yeast
  C The presence of oxygen
  D Sugar or starch dissolved in water

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5a2 marks

Ethanol is made by fermentation of a carbohydrate dissolved in water, in the presence of yeast.

The reaction is carried out at 30 °C.

Explain why the reaction is carried out at a temperature of 30 °C rather than at a temperature of 80 °C.

5b3 marks

Ethanol, C2H5OH, can be converted into ethanoic acid, CH3COOH.

 
i)
In this reaction ethanol is
 
(1)
  A hydrated
  B oxidised 
  C polymerised
  D reduced 

ii)
Draw the structure of a molecule of ethanoic acid, CH3COOH, showing all covalent bonds.
 
(2)
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6 marks
 i)
The apparatus in Figure 16 can be used to investigate the temperature rise produced in a known mass of water when a sample of ethanol is burned.
 
fig-16-q10ci-1cho-2f-paper-1-june-2019
 
Figure 16
 
The first steps of the method are
  1. put 100cm3 of water into a beaker
  2. determine the mass of the burner containing ethanol
  3. measure the initial temperature of the water
  4. place the burner under the beaker of water
  5. light the wick
 
Describe the remaining steps of the method that are needed to determine the mass of ethanol required to raise the temperature of the water by 30°C.

(3)

ii)
In a different experiment, separate samples of the alcohols methanol, ethanol, propanol, butanol and pentanol were burned to determine the mass of each alcohol that needs to be burned to raise the temperature of 100 cm3 water by 10°C.

alcohol number of carbon atoms in one molecule of alcohol

mass of alcohol burned in g

methanol 1 0.37
ethanol  2 0.28
propanol  0.25
butanol 4 0.23
pentanol 5 0.22

 

Draw a graph of the mass of each alcohol required to raise the temperature of 100 cm3 of water by 10°C against the number of carbon atoms in one molecule of that alcohol.

(3)

fig-q10cii-1cho-2f-paper-1-june-2019

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61 mark

What are the names of compounds A and B?

organic-structures

      Compound A  Compound B
  A butanoic acid  methanal
  B propanol ethanoic acid 
  C propanal ethanol
  D butanol propanoic acid 

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7a1 mark

Ethanol can be produced by the fermentation of glucose solution.

Which of these shows the word equation for the fermentation of glucose solution?

  A glucose → ethanol + water
  B glucose → ethanol + carbon dioxide 
  C glucose → ethanol + hydrogen 
  D glucose → ethanol + water + carbon dioxide
7b3 marks

The names and formulae of the first four alcohols in the homologous series of alcohols are given in Figure 12.

name of alcohol formula
methanol CH3OH
ethanol C2H5OH
propanol C3H7OH
butanol C4H9OH

Figure 12

i)
Pentanol is the next member of this series.
A molecule of pentanol contains five carbon atoms.

Suggest the formula of a molecule of pentanol.
(1)
ii)
Draw the structure of a molecule of ethanol.
Show all bonds.
(2)
7c3 marks

Ethanol is present in alcoholic drinks, such as wine.

When a bottle of wine is left open some of the ethanol reacts with the oxygen in the air to form ethanoic acid, CH3COOH, and water.

i)
Complete the equation for this reaction.

(2)

CH3CH2OH + .......................... → CH3COOH + ........................

ii)
Which calculation shows the percentage by mass of hydrogen in ethanoic acid?

(relative atomic mass of hydrogen, H = 1,
relative formula mass of ethanoic acid, CH3COOH = 60)
(1)
  A 1 over 60 cross times 100
  B 3 over 60 cross times 100
  C 4 over 60 cross times 100
  D 60 over 1 cross times 100
7d6 marks

Polymers have many uses.
However, the disposal of polymers after use can be a problem.
The uses of polymers are related to their properties.
Some uses of three common polymers are given in Figure 13.

Polymer Uses
poly(ethene) plastic bags, plastic bottles
poly(chloroethene)
(PVC)
window frames, water pipes, insulation for electrical wires
poly(tetrafluoroethene)
(PTFE, TeflonTM)
 coating for frying pans, stain‐proofing for clothing

Figure 13

Discuss the reasons for using these polymers in the ways shown in Figure 13 and the problems in disposing of these polymers.

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81 mark

Fermentation of carbohydrates produces a dilute solution of ethanol.

This need further processing by fractional distillation to produce a concentrated solution of ethanol.

Some of the steps of fractional distillation are shown below.

The steps shown are not in the correct order.

step J the ethanol evaporates
step K ethanol vapours are cooled
step L the fermentation mixture is heated to 78oC
step M ethanol vapours condense
step N ethanol vapours pass through a condenser

  

Which of the following shows the correct order of the steps above?

  A N, K, M, L, J
  B L, J, K, N, M
  C K, M, N, L, J
  D L, J, N, K, M

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9a3 marks

This question is about alcohols.

i)
Figure 14 shows an incomplete diagram of the structure of a molecule of propanol, CH3CH2CH2OH.

Complete the structure of the molecule of propanol in Figure 14.

(2)

fig-14-q7a-1cho-2f-paper-1-nov-2021

Figure 14

ii)
Propanol can be converted into propanoic acid.

What happens to propanol in this reaction?

(1)

  A it is dehydrated
  B it is neutralised
  C it is oxidised
  D it is polymerised
9b
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9 marks

A student used an alcohol burner to find the mass of different alcohols needed to raise the temperature of 100 cm3 of water by 20 °C.


Figure 15 shows their results.

alcohol initial mass of
alcohol burner and
alcohol in g
final mass of
alcohol burner and
alcohol in g
mass of alcohol
used in g
ethanol 122.51 122.02 0.49
propanol 168.55 168.13 0.42
butanol 152.62 152.23  
pentanol 67.22 66.86 0.36

Figure 15

i)
Calculate the mass of butanol used.
(1)
mass of butanol = ................... g
ii)
Figure 16 shows equipment that can be used to obtain the results shown in Figure 15.

fig-16-q7bii-1cho-2f-paper-1-nov-2021
Figure 16

Describe an experiment, using the equipment in Figure 16, that could be used to obtain results like those shown in Figure 15.

(6)

iii)
The results show that 0.36 g of pentanol was needed to raise the temperature of the water by 20 °C.

Calculate the mass of pentanol needed to raise the temperature of water by 1 °C.

Give your answer to 2 decimal places.

Show your working.
(2)


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101 mark

Which of the following statements about butanol is not correct?

  A It will undergo oxidation to form butanoic acid
  B It has the formula C4H9OH
  C In aqueous solution, it will react with an alkali to form a salt, carbon dioxide and water
  D It can be dehydrated to form butene

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1a4 marks

Figure 10 shows a flask fitted with a cotton wool plug.
The flask contains an aqueous solution of a carbohydrate.

fig-10-q10a-1cho-2h-paper-1-nov-2020

Figure 10

i)
State two steps that need to be taken to turn the solution of the carbohydrate in the flask into a solution of ethanol.
(2)
ii)
The apparatus in Figure 11 is used to increase the concentration of the dilute solution of ethanol.

fig-11-q10aii-1cho-2h-paper-1-nov-2020

Figure 11

This apparatus did not produce a very concentrated solution of ethanol.
Describe how the apparatus can be altered to produce a more concentrated solution of ethanol.

(2)

1b
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3 marks

The equation for the fermentation of a carbohydrate is

C6H12O6 → 2C2H5OH + 2CO2

Calculate the maximum mass of carbon dioxide that could be produced if 135 g of this carbohydrate is fully fermented

(relative formula masses: CO2= 44; C6H12O6= 180)

mass of carbon dioxide = ............................... g

1c6 marks

Figure 12 shows information about some compounds in the same homologous series.

fig-12-q10c-1cho-2h-paper-1-nov-2020

Figure 12

Explain, using the data in Figure 12, why these compounds belong together in the same homologous series.

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2a7 marks

Propanol, C3H7OH, can undergo reactions to form compounds Y and Z shown in Figure 14.

fig-14-q10a-1cho-2h-paper-1-nov-2021

Figure 14

i)
What happens to propanol when it forms compound Y?

(1)

  A propanol undergoes an addition reaction
  B propanol is dehydrated 
  C propanol is hydrated 
  D propanol is oxidised

ii)
Compound Y can also be formed in the following reaction

stack straight C subscript 3 straight H subscript 8 with compound space bold X below space rightwards arrow space stack straight C subscript 3 straight H subscript 6 with compound space bold Y below space plus space straight H subscript 2

Explain how bromine water can be used to distinguish between compound X and compound Y.

(3)

iii)
Compound Z is a carboxylic acid.

Which of the following shows the functional group of a carboxylic acid?
(1)
  A fig-q10iiia-1cho-2h-paper-1-nov-2021
  B fig-q10iiib-1cho-2h-paper-1-nov-2021 
  C fig-q10iiic-1cho-2h-paper-1-nov-2021 
  D fig-q10iiid-1cho-2h-paper-1-nov-2021

iv)
Compound Z is an acid and turns litmus and universal indicator papers red.
Compound Z also shows other acidic properties.

Devise an experiment that would show another acidic property of compound Z.
(2)
2b
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2 marks

Higher Only

The balanced equation for the production of ethanol from the carbohydrate sucrose is

stack straight C subscript 12 straight H subscript 22 straight O subscript 11 with sucrose belowstraight H subscript 2 straight O rightwards arrow 4 straight C subscript 2 straight H subscript 5 OH space plus space 4 CO subscript 2

Calculate the minimum mass of sucrose needed to produce 26.9 g of ethanol.
(relative formula masses: straight C subscript 2 straight H subscript 5 OH space equals space 46 comma space straight C subscript 12 straight H subscript 22 straight O subscript 11 space end subscript equals space 342)

minimum mass of sucrose = ................................. g

2c
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2 marks

Higher Only

Calculate the total number of atoms in 10.0 g of sucrose, C12H22O11.

(relative formula mass: C12H22O11 = 342; Avogadro constant = 6.02 × 1023)

number of atoms = ......................................

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3a5 marks

Propanoic acid is a carboxylic acid. Its formula is CH3–CH2–COOH.

 
i)
Propanoic acid is the third member of the homologous series of carboxylic acids.
 
Give the name and structural formula of the fourth member of this series.
 
Name ..............................................................
 
Formula ..............................................................
(2)

ii)
Members of a homologous series have very similar chemical properties.
 
State three other characteristics of a homologous series.
(3)

3b1 mark

Carboxylic acids can be made by the oxidation of alcohols.

 
Draw the structural formula of the alcohol which can be oxidised to propanoic acid.
Show all atoms and bonds.

3c2 marks

Complete the following equations for some of the reactions of propanoic acid.

 
i)
Zinc + propanoic acid → .................. .................. + hydrogen
 
(1)
 
ii)
Calcium oxide + propanoic acid → .................. + ..................
 
(1) 
3d7 marks

A piece of magnesium was added to 100 cm3 of an aqueous acid. The time taken for the metal to react completely was measured. 

This experiment was repeated using different aqueous acids. The same volume of acid was used in each experiment and the pieces of magnesium used were identical. 

In one experiment the reaction was carried out at a different temperature.

 
experiment acid concentration in mol/dm3 temperature / °C time / seconds
A propanoic 1.0 20 300
B propanoic 1.0 30 180
C propanoic 0.5 20 480
D hydrochloric 1.0 20 60
 

Explain the following in terms of collision rate between reacting particles.

 
i)
Why is the rate in experiment C slower than the rate in experiment A

(2)

ii)
Why is the rate in experiment B faster than the rate in experiment A?

(2)

iii)
Why is the rate in experiment D faster than the rate in experiment A?

(3)

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4a
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6 marks

Ethanol, C2H5OH, can be produced by the fermentation of glucose, C6H12O6

i)
Complete the equation for the fermentation of glucose.
(1)

C6H12O6  → 2C2H5OH + 2 ........................................

ii)
State why it is necessary for fermentation to be done in the absence of air.
(1)

iii)
Explain why the temperature should not be higher than 40 °C.
(2)

iv)
When 4 mol of glucose is fermented, a mass of 55.2 g of ethanol is produced.
Show that the percentage yield of ethanol is 15%.
[Mr of C2H5OH = 46]
(2)
4b4 marks

Higher Only

Ethanol can also be produced by the reaction between ethene and steam.
The equation for the reaction is

C2H4 (g) + H2O (g) rightwards harpoon over leftwards harpoon C2H5OH (g)

i)
This reaction is in dynamic equilibrium.
Give two features of a reaction in dynamic equilibrium.
(2)
ii)
When the equilibrium mixture is heated, the yield of ethanol decreases.
Explain whether the forward reaction is exothermic or endothermic.
(2)

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5a2 marks

This question is about carboxylic acids.

The table below shows information about three carboxylic acids.

Complete the table. 

 Name  Formula 
 Ethanoic acid  CH3COOH
  CH3CH2CH2COOH
 Propanoic acid  

5b3 marks

Higher Only

Solutions of ethanoic acid and hydrochloric acid have different pH levels at the same concentration.

Explain the difference in pH levels between the two acids 

5c3 marks

A student adds sodium to a solution of ethanoic acid in an open flask on a balance.

Explain what happens to the mass of the flask and its contents during the reaction.

5d2 marks

In a separate reaction, a student adds ethanoic acid to zinc carbonate.

Describe and give the result of a test the student would do to identify the gas produced.

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