Forces between molecules: AQA A‑Level Chemistry questions

AQA A-Level Chemistry past-paper questions on 3.1.3.7 Forces between molecules, 2008–2025, with mark schemes and examiner’s reports where available.

All 101 questions on Forces between molecules, as a list

June 2025, Paper 1, Q05.1 (2 marks): Explain why chlorine has a lower boiling point than bromine. [2 marks]
June 2025, AS Paper 2, Q02.3 (3 marks): Hydrogen bonds exist between molecules of liquid methanol. Draw a diagram to show a hydrogen bond between two molecules of methanol. Include all the lone pairs
June 2025, AS Paper 2, Q03 (6 marks): Molecules of CCl4 and CHCl3 have similar tetrahedral shapes. The boiling point of CCl4 is 77 °C The boiling point of CHCl3 is 61 °C Explain why CCl4 has a highe
June 2024, Paper 3, Q13 (1 mark): Which compound forms the greatest number of hydrogen bonds per molecule in the liquid state? [1 mark] A CH3CH2COOH B CH3CH2OCH3 C CH3CH2CHO D CH3CH2CH2OH
June 2024, AS Paper 1, Q03.4 (3 marks): There are van der Waals forces between non-polar molecules. Explain what causes these forces. [3 marks]
June 2024, AS Paper 2, Q07.3 (3 marks): Propanoic acid molecules cannot be separated from the reaction mixture by simple distillation because propanoic acid forms hydrogen bonds with water molecules.
June 2024, AS Paper 2, Q17 (1 mark): Which of these alkanes has the highest boiling point? [1 mark] A decane B hexane C 2,3-dimethyloctane D 2,3-dimethylbutane
June 2023, Paper 3, Q05.3 (3 marks): Explain the trend in the boiling points of the three compounds. Refer to the intermolecular forces in all three compounds in your answer. [3 marks]
June 2023, Paper 3, Q15 (1 mark): What happens when water is vaporised? [1 mark] A Covalent bonds break within molecules. B Intermolecular forces are overcome. C The enthalpy of the molecules de
June 2023, AS Paper 2, Q06.3 (2 marks): Explain why tetrachloromethane has a higher boiling point than dichloromethane. [2 marks]
June 2023, AS Paper 2, Q06.4 (2 marks): Propan-1-ol has a higher boiling point than the other two compounds because of hydrogen bonding. Describe the hydrogen bonding in propan-1-ol. [2 marks]
June 2022, AS Paper 1, Q04.1 (3 marks): Complete the diagram to show how one molecule of ammonia can form a hydrogen bond with one molecule of ethanol. Include all lone pairs of electrons and partial
June 2022, AS Paper 1, Q04.5 (3 marks): Suggest, in terms of the intermolecular forces for each compound, why CBr4 has a higher boiling point than CHBr3 [3 marks]
June 2022, AS Paper 2, Q13 (1 mark): Which compound has the highest boiling point? [1 mark] A CH3COCH2CH3 B CH3CH2CH2CH2OH C CH3CH2CH2CHO D CH3CH2CH2CH2CH3
November 2021, Paper 3, Q17 (1 mark): Which statement about (CH3)2CHCH2COOH is correct? [1 mark] A In aqueous solution it reacts with magnesium to form carbon dioxide. B It can form hydrogen bonds.
November 2021, AS Paper 1, Q05.1 (3 marks): Chlorine has a low boiling point because the forces between the molecules are weak. Explain how these forces arise between molecules of chlorine. [3 marks]
November 2021, AS Paper 2, Q03.4 (3 marks): Explain why propanone has a lower boiling point than propan-2-ol. [3 marks]
November 2020, Paper 1, Q07 (6 marks): The melting point of XeF4 is higher than the melting point of PF3 Explain why the melting points of these two compounds are different. In your answer you should
November 2020, AS Paper 1, Q11 (1 mark): Which compound has hydrogen bonding? [1 mark] A NaH B NH3 C HI D SiH4
November 2020, AS Paper 2, Q04.1 (3 marks): The boiling point of pentan-2-ol is 119 °C The boiling point of pent-1-ene is 30 °C Explain why pentan-2-ol has a higher boiling point than pent-1-ene. [3 marks
June 2019, Paper 1, Q08.1 (3 marks): Draw a diagram to show the strongest type of interaction between two molecules of ethanol (C2H5OH) in the liquid phase. Include all lone pairs and partial charg
June 2019, Paper 1, Q08.2 (3 marks): Methoxymethane (CH3OCH3) is an isomer of ethanol. Table 5 shows the boiling points of ethanol and methoxymethane. Table 5 Compound Boiling point / °C ethanol 78
June 2019, Paper 2, Q07.2 (6 marks): Explain how and why isomers X and Y can be distinguished by comparing each of their • boiling points • 13C NMR spectra • infrared spectra. Use data from Tables
June 2019, AS Paper 1, Q13 (1 mark): Which change occurs when water is vaporised? [1 mark] A An exothermic change occurs. B Covalent bonds are broken. C Intermolecular forces are overcome. D The to
June 2019, AS Paper 2, Q05.1 (3 marks): Draw a diagram to show how two methanol molecules interact with each other through hydrogen bonding in the liquid phase. Include all partial charges and all lon
June 2019, AS Paper 2, Q21 (1 mark): Which compound has the highest boiling point? [1 mark] A CH3CH2CH2Br B CH3CH2CH2F C CH3CH2CHO D CH3CH2COOH
June 2018, Paper 2, Q03.1 (3 marks): Explain, with reference to intermolecular forces, why distillation allows propanal to be separated from the other organic compounds in this reaction mixture. [3
June 2018, AS Paper 1, Q09.3 (3 marks): Silicon tetrafluoride (SiF4) is a tetrahedral molecule. Deduce the type of intermolecular forces in SiF4 Explain how this type of intermolecular force arises an
June 2018, AS Paper 2, Q04.2 (2 marks): Explain why nonane has a higher boiling point than 2,4-dimethylheptane. [2 marks]
June 2018, AS Paper 2, Q13 (1 mark): Which compound has the highest boiling point? [1 mark] A butanal B butan-2-ol C but-2-ene D 1-fluorobutane
June 2017, Paper 3, Q05 (1 mark): Which compound has the highest boiling point? [1 mark] A CH3CH2CH2OH B CH3CH2CHO C CH3COCH3 D CH3COOCH3
June 2017, AS Paper 1, Q05.2 (2 marks): Explain how permanent dipole-dipole forces arise between hydrogen chloride molecules. [2 mark
June 2017, AS Paper 2, Q07.5 (6 marks): Cyclohexene is prepared by the dehydration of cyclohexanol using concentrated phosphoric acid as a catalyst. The structure of concentrated phosphoric acid is sh
June 2017, AS Paper 2, Q09.1 (2 marks): Chloroethene has a melting point of −154 ºC All types of PVC melt at temperatures over 100 ºC Explain why PVC melts at a higher temperature than chloroethene. [
June 2016, AS Paper 2, Q04.3 (6 marks): Predict the relative boiling points of these three compounds from the highest to the lowest boiling points. Justify this order in terms of intermolecular forces
Specimen, Paper 1, Q05.3 (4 marks): Diagram Explanation
Specimen, Paper 2, Q04.6 (1 mark): List alcohol A, product B and isomer C in order of increasing boiling point. [1 mark] 0 4 . 6
Specimen, Paper 2, Q05.2 (4 marks): 5
Specimen, Paper 3, Q01.4 (2 marks): Use your knowledge of structure and bonding to explain why it is possible to separat ethanal in this way. [2 mark 0 1 . 4
Specimen, Paper 3, Q32 (1 mark): Which compound has the highest boiling point? [1 mark] A C2H4 B C2H6 C CH3NH2 D CH F 3 2 3
June 2016, CHEM1 (old spec), Q2(a) (3 marks): Van der Waals’ forces exist between all molecules. Explain how these forces arise. [3 marks]
June 2016, CHEM1 (old spec), Q2(b)(i) (3 marks): Explain, in terms of their intermolecular forces, why the boiling points of these compounds are different. [3 marks]
June 2016, CHEM1 (old spec), Q2(b)(ii) (1 mark): Suggest how a mixture of methanol and methanethiol could be separated. [1 mark]
June 2016, CHEM1 (old spec), Q2(c) (2 marks): Suggest why methaneselenol (CH3SeH) has a higher boiling point than methanethiol (CH3SH). [2 marks]
June 2015, CHEM1 (old spec), Q5(b)(i) (1 mark): State the strongest type of interaction that occurs between molecules of hydrogen peroxide and water. [1 mark]
June 2015, CHEM1 (old spec), Q5(b)(ii) (3 marks): Draw a diagram to show how one molecule of hydrogen peroxide interacts with one molecule of water. Include all lone pairs and partial charges in your diagram. [
June 2015, CHEM1 (old spec), Q5(c) (2 marks): Explain, in terms of electronegativity, why the boiling point of H2S2 is lower than H2O2. [2 marks]
June 2014, CHEM4 (old spec), Q4(a) (1 mark): Name the strongest type of interaction between polymer chains of Kevlar. [1 mark]
June 2014, CHEM1 (old spec), Q4(a)(i) (1 mark): Name the strongest attractive force between two ammonia molecules. [1 mark]
June 2014, CHEM1 (old spec), Q4(a)(ii) (3 marks): Draw a diagram to show how two ammonia molecules interact with each other in the liquid phase. Include all partial charges and all lone pairs of electrons in yo
June 2014, CHEM1 (old spec), Q5(d)(iii) (2 marks): Explain why the melting point of dodecane is higher than the melting point of the straight-chain alkane produced by cracking dodecane. [2 marks]
June 2013, CHEM1 (old spec), Q4(a) (1 mark): State the strongest type of intermolecular force between one molecule of ammonia and one molecule of water. (1 mark)
June 2013, CHEM1 (old spec), Q4(b) (3 marks): Draw a diagram to show how one molecule of ammonia is attracted to one molecule of water. Include all partial charges and all lone pairs of electrons in your di
June 2013, CHEM1 (old spec), Q4(c) (1 mark): Phosphine (PH3) has a structure similar to ammonia. In terms of intermolecular forces, suggest the main reason why phosphine is almost insoluble in water. (1 ma
June 2013, CHEM1 (old spec), Q8(a) (3 marks): The structure of the bromoalkane Z is Give the IUPAC name for Z. Give the general formula of the homologous series of straight-chain bromoalkanes that contains
June 2013, CHEM2 (old spec), Q6(c) (2 marks): Explain why chlorine has a lower boiling point than bromine.
January 2013, CHEM1 (old spec), Q4(b) (1 mark): Both C3H8 and C4H10 can be liquefied and used as fuels for camping stoves. Suggest, with a reason, which of these two fuels is liquefied more easily. (1 mark)
January 2013, CHEM1 (old spec), Q4(f)(iii) (2 marks): Ethanethiol and ethanol molecules have similar shapes. Explain why ethanol has the higher boiling point.
January 2013, CHEM1 (old spec), Q4(g)(ii) (2 marks): X has a boiling point of 9.5 ºC. Explain why the boiling point of X is lower than that of its straight-chain isomer.
June 2012, CHEM5 (old spec), Q1(c) (2 marks): Explain why phosphorus(V) oxide has a higher melting point than sulfur(VI) oxide.
June 2012, CHEM1 (old spec), Q2(e) (2 marks): Explain why the boiling points of X and Y are similar.
June 2012, CHEM1 (old spec), Q3(d) (1 mark): Although phosphine molecules contain hydrogen atoms, there is no hydrogen bonding between phosphine molecules. Suggest an explanation for this. (1 mark)
January 2012, CHEM4 (old spec), Q8(b)(iii) (2 marks): Explain why the polymer in part (b) (ii) has a higher melting point than the polymer in part (b) (i). (2 marks)
January 2012, CHEM5 (old spec), Q2(b) (2 marks): Use your knowledge of bonding to explain why ΔH is positive for this process. (2 marks)
January 2012, CHEM5 (old spec), Q3(a)(ii) (2 marks): sulfur dioxide has a low melting point.
January 2012, CHEM5 (old spec), Q3(b) (2 marks): Explain why the melting point of P4O10 is higher than the melting point of SO2
January 2012, CHEM1 (old spec), Q1(d)(i) (1 mark): State the strongest type of intermolecular force between hydrogen fluoride molecules. (1 mark)
January 2012, CHEM1 (old spec), Q1(d)(ii) (3 marks): Draw a diagram to show how two molecules of hydrogen fluoride are attracted to each other by the type of intermolecular force that you stated in part (d) (i). I
January 2012, CHEM1 (old spec), Q1(e) (2 marks): The boiling points of fluorine and hydrogen fluoride are –188 oC and 19.5 oC respectively. Explain, in terms of bonding, why the boiling point of fluorine is ve
June 2011, CHEM4 (old spec), Q4(a)(ii) (3 marks): In terms of the intermolecular forces between the polymer chains, explain why polyamides can be made into fibres suitable for use in sewing and weaving, whereas
June 2011, CHEM1 (old spec), Q3(a) (2 marks): Explain why iodine has a higher melting point than fluorine. (2 marks)
June 2011, CHEM1 (old spec), Q3(c) (1 mark): State the strongest type of intermolecular force in a sample of NHF2 (1 mark)
January 2011, CHEM1 (old spec), Q1(a) (1 mark): The following diagram shows the arrangement of some of the water molecules in a crystal of ice. With reference to the structure shown above give one reason why
January 2011, CHEM1 (old spec), Q1(b)(i) (1 mark): State the strongest type of intermolecular force holding the water molecules together in the ice crystal. (1 mark)
January 2011, CHEM1 (old spec), Q1(b)(ii) (1 mark): State the strongest type of intermolecular force in methane. (1 mark)
January 2011, CHEM1 (old spec), Q1(b)(iii) (1 mark): Give one reason why the melting point of ice is higher than the melting point of methane. (1 mark)
January 2011, CHEM1 (old spec), Q6(d) (2 marks): Suggest why the branched chain isomer shown above has a lower boiling point than octane.
June 2010, CHEM1 (old spec), Q1(c) (1 mark): Suggest the strongest type of intermolecular force between CCI2F2 molecules. (1 mark)
June 2010, CHEM1 (old spec), Q7(c) (2 marks): Explain why iodine vaporises when heated gently.
January 2010, CHEM1 (old spec), Q3(a) (2 marks): State the strongest type of intermolecular force in water and in hydrogen sulfide (H2S). Water Hydrogen sulfide (2 marks)
January 2010, CHEM1 (old spec), Q3(b) (3 marks): Draw a diagram to show how two molecules of water are attracted to each other by the type of intermolecular force you stated in part (a). Include partial charge
January 2010, CHEM1 (old spec), Q3(c) (1 mark): Explain why the boiling point of water is much higher than the boiling point of hydrogen sulfide. (1 mark)
January 2010, CHEM1 (old spec), Q3(d) (2 marks): Explain why the boiling points increase from H2S to H2Te (2 marks)
June 2009, CHEM1 (old spec), Q3(a)(ii) (2 marks): 3 (a) (ii) State the strongest type of intermolecular force present in each compound. Liquid ethanol Liquid propane (2 marks)
June 2009, CHEM1 (old spec), Q3(b) (3 marks): 3 (b) Ethanol dissolves in water. Draw a diagram to show how one molecule of ethanol interacts with one molecule of water in the solution. Include partial charg
June 2009, CHEM1 (old spec), Q4(d)(i) (2 marks): 4 (d) (i) Explain the trend in these boiling points. (2 marks)
June 2009, CHEM2 (old spec), Q3(b) (1 mark): 3 (b) The students deduced that the heat change was due only to the formation of intermolecular forces between ethyl ethanoate molecules and trichloromethane mo
January 2009, CHEM1 (old spec), Q2(b) (2 marks): 2 (b) State the strongest type of intermolecular force in the following compounds. Methane (CH4) Ammonia (NH3) (2 marks)
January 2009, CHEM1 (old spec), Q2(c) (3 marks): 2 (c) Use the values in the table to explain how the strongest type of intermolecular force arises between two molecules of ammonia. (3 marks)
January 2009, CHEM1 (old spec), Q2(f) (1 mark): 2 (f) The boiling point of AsH3 is –62.5 °C and the boiling point of NH3 is –33.0 °C. Suggest why the boiling point of AsH3 is lower than that of NH3 (1 mark)
January 2009, CHM1 (2008 spec), Q3(b) (2 marks): 3 (b) Explain the heat energy change associated with boiling. (2 marks)
January 2009, CHM1 (2008 spec), Q3(c)(i) (2 marks): 3 (c) (i) Define the term electronegativity. (2 marks)
January 2009, CHM1 (2008 spec), Q3(c)(ii) (2 marks): 3 (c) (ii) Explain, in terms of electronegativity, why hydrogen bonds form between H2O molecules but not between H2S molecules. (2 marks)
January 2009, CHM1 (2008 spec), Q3(c)(iii) (1 mark): 3 (c) (iii) Explain, in terms of the intermolecular forces present, why the boiling point of H2S is so much lower than that of H2O (1 mark)
January 2009, CHM1 (2008 spec), Q3(c)(iv) (1 mark): 3 (c) (iv) Identify an element, other than oxygen, that when bonded to hydrogen can be involved in hydrogen bonding. (1 mark)
January 2009, CHM1 (2008 spec), Q3(d) (3 marks): 3 (d) Draw a diagram to show how two molecules of water are attracted to each other by hydrogen bonding. Include partial charges and all lone pairs of electrons
January 2009, CHM1 (2008 spec), Q5(a)(i) (3 marks): 5 (a) (i) Describe the structure of, and the bonding in, solid iodine. (3 marks)
January 2009, CHM1 (2008 spec), Q5(a)(ii) (2 marks): 5 (a) (ii) Explain the trend in the melting points of the halogens shown in the table above. (2 marks)
June 2008, CHM5 (2008 spec), Q2(d) (3 marks): 2 (d) Explain in terms of intermolecular forces why the enthalpy of vaporisation for liquid hydrogen fluoride is greater than that for liquid ammonia. (3 marks)
January 2008, CHM1 (2008 spec), Q3(d) (6 marks): (d) The boiling points of some hydrogen halides are shown in the table below. Explain, in terms of the intermolecular forces present, why Hydrogen halide HF HCl
January 2008, CHM4 (2008 spec), Q5(d) (2 marks): (d) (i) Name the strongest type of intermolecular force in polymer R. (ii) Name the strongest type of intermolecular force in polymer T. (2 marks)

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