Distinguish between a sigma and pi bond.

Identify the hybridization of carbon in ethane, ethene and ethyne.

State, giving a reason, if but-1-ene exhibits cis-trans isomerism.

State the type of reaction which occurs between but-1-ene and hydrogen iodide at room temperature.

Explain the mechanism of the reaction between but-1-ene with hydrogen iodide, using curly arrows to represent the movement of electron pairs.

State, giving a reason, if the product of this reaction exhibits stereoisomerism.

Deduce the rate expression for this reaction.

Deduce the units of the rate constant.

Determine the initial rate of reaction in experiment 4.

Deduce, with a reason, the mechanism of the reaction between 2-chloropentane and sodium hydroxide.

Discuss the reason benzene is more reactive with an electrophile than a nucleophile.

Sigma (σ) bond:

overlap «of atomic orbitals» along the axial / intermolecular axis / electron density is between nuclei
OR
head-on/end-to-end overlap «of atomic orbitals» ✔

Pi (π) bond:

overlap «of p-orbitals» above and below the internuclear axis/electron density above and below internuclear axis
OR
sideways overlap «of p-orbitals» ✔

Accept a suitable diagram.

All 3 required for mark.

no AND 2 groups on a carbon «in the double bond» are the same/hydrogen «atoms»

OR

no AND molecule produced by rearranging atoms bonded on a carbon «in the double bond» is the same as the original ✔

«electrophilic» addition ✔

Do not allow nucleophilic addition.

curly arrow going from C=C to H of HI AND curly arrow showing I leaving ✔

representation of carbocation ✔

curly arrow going from lone pair/negative charge on I^– to C⁺ ✔

2-iodobutane formed ✔

Penalize incorrect bond, e.g. –CH–H₃C or –CH₃C once only.

yes AND has a carbon attached to four different groups
OR
yes AND it contains a chiral carbon ✔

Accept yes AND mirror image of molecule different to original/non-superimposable on original.

«rate =» k[NaOH][C₅H₁₁Cl] ✔

mol^–1dm³s^–1 ✔

ALTERNATIVE 1:

«k = » 1.25 «mol^–1dm³s^–1» ✔

«rate = 1.25 mol^–1dm³s^–1 × 0.60 mol dm^–3 × 0.25 mol dm^–3»

1.9 x 10^–1 «mol dm^–3s^–1» ✔

ALTERNATIVE 2:

«[NaOH] exp. 4 is 3 × exp. 1»

«[C₅H₁₁Cl] exp. 4 is 2.5 × exp. 1»

«exp. 4 will be » 7.5× faster ✔

1.9 x 10^–1 «mol dm^–3s^–1» ✔

Award [2] for correct final answer.

S_N2 AND rate depends on both OH^– and 2-chloropentane ✔

Accept E2 AND rate depends on both OH^– and 2-chloropentane.

delocalized electrons/pi bonds «around the ring»
OR
molecule has a region of high electron density/negative charge ✔

electrophiles are attracted/positively charged AND nucleophiles repelled/negatively charged ✔

Do not accept just “nucleophiles less attracted” for M2.

Accept “benzene AND nucleophiles are both electron rich” for “repels nucleophiles”.