Edexcel IAL Chemistry AS Topic 4 Organic chemistry and alkanes

Pearson Edexcel IAL Chemistry syllabusChemistry YCH11First assessment 2019

Identify the functional group and longest chain, apply locants and formula conventions and use the stated reagent or hazard evidence to classify the reaction or decision.

Exam points

Name and draw organic compounds using longest chains, locants and functional groups.
Convert among molecular, empirical, structural and displayed formulae accurately.
Apply hazard and reaction evidence to alkane practicals and reaction terminology.

[Maximum number: 2]

A sequence of four molecules is shown.

(a)

What is the molecular formula for the fifth molecule in this sequence?

$\mathrm{CH}_{4} \mathrm{O}$

$\mathrm{C}_{6} \mathrm{H}_{11} \mathrm{O}$

$\mathrm{C}_{6} \mathrm{H}_{14} \mathrm{O}$

$\mathrm{C}_{7} \mathrm{H}_{16} \mathrm{O}$

[ 1 ]

(b)

What is the name of this type of sequence?

functional group

homologous series

homolytic series

skeletal formulae

[ 1 ]

What is the IUPAC name of this alkane?

□ A 2-ethyl-4,5-dimethylheptane
□ B 6-ethyl-3,4-dimethylheptane
□ C 3,4,6-trimethyloctane
□ D 3,5,6-trimethyloctane

[Maximum number: 4]

Cyclopentane undergoes free radical substitution with bromine.

(a)

Which of these is an overall equation for this reaction?
□

A $\mathrm{C}_{5} \mathrm{H}_{8}+\mathrm{Br}_{2} \rightarrow \mathrm{C}_{5} \mathrm{H}_{8} \mathrm{Br}_{2}$

□

B $\mathrm{C}_{5} \mathrm{H}_{10}+\mathrm{Br}_{2} \rightarrow \mathrm{C}_{5} \mathrm{H}_{10} \mathrm{Br}_{2}$

□

C $\mathrm{C}_{5} \mathrm{H}_{10}+\mathrm{Br}_{2} \rightarrow \mathrm{C}_{5} \mathrm{H}_{8} \mathrm{Br}_{2}+\mathrm{H}_{2}$

□

D $\mathrm{C}_{5} \mathrm{H}_{10}+\mathrm{Br}_{2} \rightarrow \mathrm{C}_{5} \mathrm{H}_{9} \mathrm{Br}+\mathrm{HBr}$

[ 1 ]

(b)

Which statement is not correct about this reaction system?

only the initiation step involves homolytic bond fission

only some bromine is converted to free radicals in the initiation step

propagation forms more product than termination

further substitution reactions are likely to occur

[ 1 ]

(c)

Which free radical is least likely to form in a propagation step in this reaction system?

$\mathrm{C}_{5} \mathrm{H}_{9}^{\bullet}$

$\mathrm{Br}^{\bullet}$

$\mathrm{C}_{5} \mathrm{H}_{8} \mathrm{Br}^{\bullet}$

$\mathrm{H}^{\text {• }}$

[ 1 ]

(d)

Which alkane could be formed in a termination step in this reaction system?
□ A

□ B

□ C

□ D

[ 1 ]

[Maximum number: 2]

Methane reacts with excess chlorine in UV light.

(a)

Which process occurs in the initiation step?
□ A

□ B

□ c Cl-Cl
□

D $\mathrm{Cl} \stackrel{\vdash}{\leftarrow} \mathrm{Cl}$

[ 1 ]

(b)

Which of these molecules could not be formed in a termination step?

$\mathrm{C}_{2} \mathrm{H}_{6}$

$\mathrm{CH}_{3} \mathrm{Cl}$

$\mathrm{CH}_{2} \mathrm{Cl}_{2}$

HCl

[ 1 ]

[Maximum number: 9]

This question is about hexane, $\mathrm{C}_{6} \mathrm{H}_{14}$ .

(a)

The skeletal formula of hexane is

Draw the four structural isomers of hexane in the boxes.

[ 4 ]

(b)

Hexane reacts with bromine in the presence of ultraviolet radiation to form a mixture of bromoalkanes.

[ 5 ]

(i)

Draw the initiation step of this reaction, using curly half-arrows.

[ 2 ]

(ii)

Write equations for two propagation steps to show how $\mathrm{C}_{6} \mathrm{H}_{13} \mathrm{Br}$ is formed. Curly arrows are not required.

[ 2 ]

(iii)

Give the molecular formula of an alkane formed in a termination step in this reaction.

[ 1 ]

[Maximum number: 4]

This question is about ethene, $\mathrm{C}_{2} \mathrm{H}_{4}$ .

(a)

Ethene and chlorine react to form 1,2-dichloroethane.

[ 2 ]

(i)

One hazard symbol for 1,2-dichloroethane is shown.

By identifying this hazard, give one way of minimising the risk when working with 1,2-dichloroethane in a laboratory.

Assume the use of safety goggles and a laboratory coat.

[ 2 ]

(b)

Ethene reacts with buta-1,3-diene to form cyclohexene as the only product.

Complete the equation for the formation of cyclohexene from ethene and buta-1,3-diene using skeletal formulae.

[ 1 ]

(c)

Two reactions of cyclohexene are shown.

[ 1 ]

(i)

Classify the type of reaction occurring in Reaction 1.

[ 1 ]

[Maximum number: 4]

This question is about the production of squalane, a liquid alkane which occurs naturally in human skin and is used in cosmetics.

squalane

(a)

Give the molecular formula of squalane.

[ 1 ]

(b)

The compound alpha-farnesene, $\mathrm{C}_{15} \mathrm{H}_{24}$ , is a structural isomer of beta-farnesene. The structural formula of alpha-farnesene is

\left(\mathrm{CH}_{3}\right)_{2} \mathrm{C}=\mathrm{CHCH}_{2} \mathrm{CH}_{2} \mathrm{C}\left(\mathrm{CH}_{3}\right)=\mathrm{CHCH}_{2} \mathrm{CH}=\mathrm{C}\left(\mathrm{CH}_{3}\right) \mathrm{CH}=\mathrm{CH}_{2}

[ 3 ]

(i)

State what is meant by the term structural isomers.
(2)

[ 2 ]

(ii)

Complete the diagram to show another structural isomer of $\mathrm{C}_{15} \mathrm{H}_{24}$ . $\left(\mathrm{CH}_{3}\right)_{2} \mathrm{C}=\mathrm{CHCH}_{2} \mathrm{CH}_{2} \mathrm{C}\left(\mathrm{CH}_{3}\right)=\mathrm{CHCH}_{2} \mathrm{CH}=\mathrm{C}\left(\mathrm{CH}_{3}\right) \mathrm{CH}=\mathrm{CH}_{2}$

[ 1 ]

Exam points

Question 8

Question 8(a)

Question 8(b)

Question 14

Question 16

Question 16(a)

Question 16(b)

Question 16(c)

Question 16(d)

Question 10

Question 10(a)

Question 10(b)

Question 20

Question 20(a)

Question 20(b)

Question 20(b)(i)

Question 20(b)(ii)

Question 20(b)(iii)

Question 21

Question 21(c)

Question 21(c)(ii)

Question 21(e)

Question 21(f)

Question 21(f)(i)

Question 21

Question 21(b)

Question 21(f)

Question 21(f)(i)

Question 21(f)(iii)