（a） $$$\mathrm{C}_{3} \mathrm{H}_{6}$$$ reacts with $$$\mathrm{HBr}(\mathrm{g})$$$ in an addition reaction．（i）Define addition reaction． . （ii）Complete Fig． 3.1 to show the mechanism for the addition reaction between $$$\mathrm{C}_{3} \mathrm{H}_{6}$$$ and HBr to produce 2－bromopropane．Include charges，dipoles，lone pairs of electrons and curly arrows，as appropriate．（iii）Explain why the major product of this reaction is 2－bromopropane rather than NIOCYW SIH $$$\perp$$$ NI ヨHYM $$$\perp$$$ ON OO NIOYVW SIH $$$\perp$$$ NI ヨHYM $$$\perp$$$ ON OO ［4］ 1－bromopropane． . . ［2］

Chemistry

IGCSE&ALevel

CAIE

Exam No：9701_s25_qp_22 Year：2025 Question No：3(a)

Answer:

Knowledge points:

13.2.1.1 homologous series

13.2.1.2 saturated and unsaturated

13.2.1.3 homolytic and heterolytic fission

13.2.1.4 free radical, initiation, propagation, termination (the use of arrows to show movement of single electrons is not required)

13.2.1.5 nucleophile, electrophile, nucleophilic, electrophilic

13.2.1.6 addition, substitution, elimination, hydrolysis, condensation

13.2.1.7 oxidation and reduction (in equations for organic redox reactions, the symbol [O] can be used to represent one atom of oxygen from an oxidising agent and the symbol [H] one atom of hydrogen from a reducing agent)

13.2.2.1 free-radical substitution

13.2.2.2 electrophilic addition

13.2.2.3 nucleophilic substitution

13.2.2.4 nucleophilic addition (in organic reaction mechanisms, the use of curly arrows to represent movement of electron pairs is expected; the arrow should begin at a bond or a lone pair of electrons)

13.3.1 describe organic molecules as either straight-chained, branched or cyclic

13.3.2 describe and explain the shape of, and bond angles in, molecules containing sp, sp2 and sp3 hybridised atoms

13.3.3 describe the arrangement of σ and π bonds in molecules containing sp, sp2 and sp3 hybridised atoms

13.3.4 understand and use the term planar when describing the arrangement of atoms in organic molecules, for example ethene

Answer:

Knowledge points:

Solution:

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