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May 2025 Section II

0/46 marks

2025 · 7 questions · 40 parts · 46 marks

0Correct0Partial0Wrong40Unattempted
1(A)(i)1(A)(ii)1(B)(i)1(B)(ii)1(C)1(D)1(E)(i)1(E)(ii)1(E)(iii)1(F)2(A)2(B)(i)2(B)(ii)2(B)(iii)2(C)2(D)3(A)3(B)(i)3(B)(ii)3(C)3(D)3(E)3(F)(i)3(F)(ii)4(A)4(B)4(C)(i)4(C)(ii)5(A)5(B)5(C)5(D)6(A)6(B)6(C)6(D)7(A)7(B)(i)7(B)(ii)7(C)
Context for question 4
A scientist is investigating the properties of a mixture of CH3​OH and H2​CO. The scientist generates the following diagram to represent the mixture.
Lewis structures of CH3OH and H2CO molecules in the mixture
4(A)Covalent Bonding, Lewis Structures and Molecular ShapeEasy1 mark
Identify the hybridization of the valence orbitals of the C atom in the H2​CO molecule.
4(B)Intermolecular Forces, Structure and Properties of SubstancesEasy1 mark
In the diagram provided, draw a SINGLE dashed line (----) to represent a strong hydrogen-bonding attraction between one CH3​OH molecule and one H2​CO molecule in the mixture.
Context for 4(C)
The scientist plans to cool a gaseous mixture of CH3​OH and H2​CO to form a liquid mixture and finds data on the two compounds. The data are summarized in the table.
SubstanceMelting Point (K)Boiling Point (K)Enthalpy of Vaporization (kJ/mol)
CH3​OH17633837.6
H2​CO18125424.2
4(C)(i)States of Matter and Gas LawsEasy1 mark
Propose a temperature to which the mixture should be cooled such that CH3​OH and H2​CO will both be liquids.
4(C)(ii)Enthalpy Changes, Calorimetry and Hess's LawEasy1 mark
The scientist analyzes the mixture after it is cooled and determines that 8.59 g of CH3​OH(l) is present. Calculate the amount of thermal energy, in kJ, that was removed to condense the 8.59 g of CH3​OH (molar mass 32.04 g/mol) at its boiling point.
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