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IB Chemistry SL 2.4 From Models to Materials Questions

Practise IB Chemistry SL 2.4 with evidence-led questions on energy, spontaneity, entropy, enthalpy and chemical reactions.

Syllabus
First assessment 2025
Course
Chemistry SL
Level
SL

Exam points

  • Identify predominant bonding in metals, ionic compounds and covalent materials, while recognizing the limits of simple categories.
  • Use electronegativity to compare ionic and covalent character and justify a bonding classification.
  • Explain how alloy composition changes lattice structure, hardness, strength and suitability for a use.
  • Relate polymer chain structure and cross-linking to melting point, flexibility, use and environmental impact.
  • Deduce alkene monomers and repeating units for addition polymers and identify the consumed double bond.

Covered syllabus points

2.4.1—Bonding continuum2.4.2—Bonding triangle2.4.3—Alloys2.4.4—Polymers2.4.5—Addition polymers

Question 1

[Maximum number: 3]

Iron may be extracted from iron (II) sulfide, FeS.

Question (a)

(a)

Iron (II) sulfide, FeS , is ionically bonded.

[ 1 ]

Question (i)

(i)

Suggest why chemists find it convenient to classify bonding into ionic, covalent and metallic.

[ 1 ]

Question (b)

(b)

Explain why the addition of small amounts of carbon to iron makes the metal harder.

[ 2 ]

Question 2

[Maximum number: 1]

Iron(II) sulfide can be produced by heating powdered iron and sulfur together.

Outline why solid iron(II) sulfide is a polar covalent compound. Use sections 9 and 17 of the data booklet.

Question 3

[Maximum number: 2]

Titanium is a transition metal.

Explain why an aluminium-titanium alloy is harder than pure aluminium.

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