IB Chemistry SL 3.4 Electron Pair Sharing Reactions Questions

Practise IB Chemistry SL 3.4 with questions on nucleophiles, electrophiles, curly-arrow notation, substitution, addition and complex ions.

Exam points

Identify nucleophiles and electrophiles, then use curly arrows to show heterolytic fission and substitution products.
Deduce electrophilic addition products for alkenes with water, halogens and hydrogen halides.
Classify Lewis acids and bases and explain coordination bonds in complex ions.

Covered syllabus points

3.4.1—Nucleophiles 3.4.2—Nucleophilic substitution 3.4.3—Heterolytic fission 3.4.4—Electrophiles 3.4.5—Electrophilic addition to alkenes 3.4.6—Lewis acid-base theory 3.4.7—Coordination bond formation 3.4.8—Complex ions

[Maximum number: 3]

Chlorine undergoes many reactions.

(a)

Predict, giving a reason, whether ethane or chloroethane is more reactive.

[ 1 ]

chloroethane AND C-Cl bond is weaker/ $324 \mathrm{~kJ} \mathrm{~mol}^{-1}$ than C-H bond $/ 414 \mathrm{~kJ} \mathrm{~mol}^{-1}$

OR

chloroethane AND contains a polar bond

Marking guidance:

Accept "chloroethane AND polar".

(b)

Write the equation for the reaction of chloroethane with a dilute aqueous solution of sodium hydroxide.

[ 1 ]

$\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{Cl}(\mathrm{l})+\mathrm{OH}^{-}(\mathrm{aq}) \rightarrow \mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{OH}(\mathrm{aq})+\mathrm{Cl}^{-}(\mathrm{aq})$

OR
$\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{Cl}(\mathrm{l})+\mathrm{NaOH}(\mathrm{aq}) \rightarrow \mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{OH}(\mathrm{aq})+\mathrm{NaCl}(\mathrm{aq})$

Marking guidance:

Accept use of $\mathrm{C}_{2} \mathrm{H}_{5} \mathrm{Cl}$ and $\mathrm{C}_{2} \mathrm{H}_{5} \mathrm{OH} / \mathrm{C}_{2} \mathrm{H}_{6} \mathrm{O}$ in the equation.

(c)

Deduce the nucleophile for the reaction in d(iii).

[ 1 ]

hydroxide «ion»/ $\mathrm{OH}^{-}$

Marking guidance:

Do not accept NaOH.

[Maximum number: 1]

Which row correctly shows heterolytic fission?

$\mathrm{Br} \underset{\mathrm{Br}}{\curvearrowleft} \rightarrow \mathrm{Br}^{+}+\mathrm{Br}^{-}$

$\mathrm{Br} \underset{\mathrm{Br}}{\curvearrowleft} \rightarrow 2 \mathrm{Br}$ .

$\mathrm{Br} \stackrel{\mathrm{Br}}{\mathrm{Br}} \rightarrow \mathrm{Br}^{+}+\mathrm{Br}^{-}$

$\mathrm{Br} \stackrel{\mathrm{Br}}{\mathrm{Br}} \rightarrow 2 \mathrm{Br}$ .

All question bank results loaded

Covered syllabus points

Question 1

Question (a)

Question (b)

Question (c)

Question 2