Chemistry 91165 (2.5) Exam

Level 2 Chemistry

91165 (2.5): Demonstrate understanding of the properties of selected organic compounds

Credits: Four

You should answer ALL parts of ALL questions in this booklet.

If you need more space for any answer, use the page(s) provided at the back of this booklet and clearly number the question.

Check that this booklet has pages 2–13 in the correct order and that none of these pages is blank.

YOU MUST HAND THIS BOOKLET TO YOUR TEACHER AT THE END OF THE ALLOTTED TIME.

SAMPLE PAPER 2

This page has been deliberately left blank

Assessor’s use only

You are advised to spend 60 minutes answering the questions in this booklet.

QUESTION ONE

(a) The following diagram shows four repeating sections of the polymer commonly called polypropene.

Draw the structural formula of the monomer molecule used to make this polymer.

(b) The organic compound with the molecular formula C2H2Cl2 can exist as two structural isomers.

Draw the TWO structural isomers of C₂H₂Cl₂ in the boxes below AND name the isomers.

Name: Name:

Assessor’s use only

(c) One of the structural isomers from (b) can exist as geometric isomers (cis-trans).

(i) Name the isomer that can exist as geometric isomers.

(ii) Draw the geometric isomers of this molecule in the table below.

cis isomer trans isomer

(d) Discuss why the organic molecule C₂H₄Cl₂ forms structural isomers but does not form geometric isomers whereas the molecule C₂H₂Cl₂ forms both structural AND geometric isomers.

In your answer, you must include:

• a description of each type of isomer (geometric or structural)

• the characteristics of molecules that form these types of isomers

• the structural formulae and functional groups of both C2H4Cl2 AND C2H2Cl2.

Assessor’s use only

This page has been deliberately left blank

Assessor’s use only

QUESTION TWO

(a) (i) Complete the table below by giving:

• the structural formula OR IUPAC (systematic) name for the organic substances A–E

• the homologous series to which each of the organic substances belongs.

Organic

substances Structural formula IUPAC (systematic) name

Homologous series

A 1-aminopropane

B methanol

C

D

E

(ii) Circle the functional group on the structural formula of each organic substance in the table above.

Assessor’s use only

(b) Five colourless organic solutions that have no labels on the their bottles are known to be:

• ethanoic acid

• aminoethane

• ethanol

• hexane

• hex-1-ene.

Discuss how each of these samples can be identified using only water, red and blue litmus paper, and bromine water.

In your answer, you must include a coherent scheme that would allow another student to follow your method, along with:

• the reagent used

• observations

• chemical equations that show the species reacting and products formed.

Assessor’s use only

Assessor’s use only

QUESTION THREE

(a) The flow diagram below shows some reactions involving organic substances.

Compound A has a molecular formula C₃H₈O. It reacts readily with acidified potassium dichromate solution.

Write the structural formula of Compound A in the box in the flow diagram above.

(b) Use the information from the flow diagram in (a) to:

(i) Write the structural formulae for Compound B in the box in the flow diagram above.

(ii) Write the name OR formula of Reactant P, Reactant Q, and Reactant R. State any conditions for the reaction to occur.

Reactant P:

Reactant Q:

Reactant R:

Assessor’s use only

(c) The types of reactions in the flow diagram on the opposite page can be described as addition, elimination, or substitution reactions.

(i) Allocate these reaction types to each of the four reactions occurring in the flow diagram on the opposite page.

(1) Compound A  C₃H₇Cl Reaction type:

(2) C3H7Cl  Compound B Reaction type:

(3) Compound A  C3H6 Reaction type:

(4) C₃H₆  C₃H₇Cl Reaction type:

(ii) Compare and contrast the similarities and differences between addition, elimination, and substitution reactions. You should use the examples of the reactions from (c) (i) in your answer.

Assessor’s use only

Extra paper for continuing your answers, if required.

Clearly number the question.

Question number

Assessor’s use only

Extra paper for continuing your answers, if required.

Clearly number the question.

Question number