RECOGNISING FUNCTIONAL GROUPS - Chemteach

UNIT 8946: SAMPLE ACTIVITY 26 SAMPLE ASSESSMENT ACTIVITIES AND SCHEDULES 6.117

8946 CHEMISTRY
LEVEL 2

RECOGNISING FUNCTIONAL GROUPS

This activity assesses:

Unit: 8946 Characterise the properties and reactions of selected organic families (Level 2).
Element: 2 Recognise the characteristic reactions of unsaturated organic substances.
3 Describe the characteristic properties and reaction of some simple functional groups.

CONDITIONS: Task A—Individual open book practical; Tasks B and C—Formal classroom activity; Task
D, E—Formal classroom activity.

INSTRUCTIONS:

Task A
Your task is to classify three substances, A, B and C, as either saturated or unsaturated.

Bromine Water Test

1 Place 10 drops of substance A in one test tube, 10 drops of substance B in another
test tube and 10 drops of substance C in a third test tube.

Add 1 mL of bromine water to each tube, cork and shake.

2 Record your observations in the results table.

Acidified Permanganate Test

1 Place 10 drops of substance A in one test tube, 10 drops of substance B in another
test tube and 10 drops of substance C in a third test tube.
Add 2 mL of acidified permanganate solution to each tube, cork and shake.

2 Record your observations in the results table.

Bromine Water Test Substance B Substance C
Substance A

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6.118 SAMPLE ASSESSMENT ACTIVITIES AND SCHEDULES UNIT 8946: SAMPLE ACTIVITY 26

Acidified Permanganate Test Substance B Substance C
Substance A

Conclusion
Use your observations to identify the hydrocarbons as saturated or unsaturated.
Substance A
Substance B
Substance C

2.1‰

Task B

Under suitable conditions, alkenes and alkynes undergo addition reactions. Draw structural
formulae for the product formed in each of the following addition reactions.

1 CH2 = CH2 + HCl Pt
2 CH2 = CH2 + H2O
3 CH3 - CH = CH2 + Cl2

4 CH ≡ CH + 2H2 2.2‰

Task C

Addition polymers are formed by the addition of individual monomer units. Draw a segment
of the polymer formed when each of the monomers shown below are joined to each other, ie
polymerised.

1H H

CC Polymerisation

HH

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UNIT 8946: SAMPLE ACTIVITY 26 SAMPLE ASSESSMENT ACTIVITIES AND SCHEDULES 6.119

2 Cl H

CC Polymerisation

HH

3H CH3

CC Polymerisation

HH

4F F

CC Polymerisation

FF

2.3‰

Task D

Alcohols, carboxylic acids and esters can be distinguished by their physical or chemical
properties. You have been given samples of six unknowns, and you are asked to identify
them by carrying out the following tests.

a) Oxidation with acidified potassium dichromate K2Cr2O7

1 mL of acidified potassium dichromate is added to 1 mL samples of each of the
unknowns. The test tubes are placed in a boiling water bath for two minutes. Record
your observations in the table below.

b) pH test

The pH of each of the unknowns is tested with universal indicator. Record your
observations in the table below.

c) Odour test

The odour of the remaining volume of each sample is carefully wafted towards your
nose. Describe the smell, eg fruity, sharp, etc.

From your observations, decide for each sample if it is an alcohol, carboxylic acid or an
ester. Enter your conclusion in the last column of the table.

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6.120 SAMPLE ASSESSMENT ACTIVITIES AND SCHEDULES UNIT 8946: SAMPLE ACTIVITY 26

Sample Oxidation test pH test Odour Functional group

A

B

C

D

E

F
3.1‰

Task E

1 Carboxylic acids can be formed by the oxidation of alcohols. Write equations for the
following reactions by giving the structural formula or name of the carboxylic acid
product.
[o] stands for excess of oxidising agent

a) propanol [o]
b) methanol [o]
c) ethanol [o]
d) pentan-1-ol [o]

2 Esters are formed when carboxylic acids react with alcohols in the presence of a
suitable catalyst. Complete the following equations, giving the name or structural
formula of the organic product formed.

a) ethanol + methanoic acid

b) propan-1-ol + ethanoic acid

c) methanol + butanoic acid

3.2‰

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UNIT 8946: SAMPLE ACTIVITY 26 SAMPLE ASSESSMENT ACTIVITIES AND SCHEDULES 6.121

Assessment Schedule: Recognising functional groups
Unit Standard 8946

Task Element and Evidence Judgement
Number Performance (The answers or performance expected from the (A statement that defines the

Criteria students) standard to be achieved)

A 2.1 Bromine water test Two out of three

hydrocarbons are correctly

Saturated Unsaturated identified with matching

slowly decolourised or observations as in evidence
decolourises/no brownÆcolourless table.

change (depending

on time of test)

Acidified permanganate test

Saturated Unsaturated
no change
decolourised to pale
pink or

purpleÆbrown

A, B and C saturated or unsaturated as
appropriate.

B 2.2 1. H H 2. H H Three out of four formulae

correct.

H C C Cl H C C OH

HH HH

3. H H H 4. H H

H C C C Cl HCCH

H Cl H HH

C 2.3 1. H H H H 2. H H H H Three out of four polymers

correctly drawn with at least

CCCC C C C C two monomers connected.

HHHH Cl H Cl H Some indication that the
3. H CH3 H CH3 4. F F F F polymer continues at either
end must be included.
CCCC CCCC
Bonds between C atoms
must be single.

HHHH FFFF

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6.122 SAMPLE ASSESSMENT ACTIVITIES AND SCHEDULES UNIT 8946: SAMPLE ACTIVITY 26

Task Element and Evidence Judgement
Number Performance (The answers or performance expected from the (A statement that defines the

Criteria students) standard to be achieved)

D 3.1 Observations and identification of given Four out of six correct

samples as appropriate. identifications.

Observations should match
the identifications.

E 3.2 1 a) CH3CH2COOH or propanoic acid Three out of four structural

formulae or names correct.

b) HCOOH or methanoic acid

c) CH3COOH or ethanoic acid

d) CH3CH2CH2CH2COOH or pentanoic
acid

2 a) ethylmethanoate or Two out of three names or
O structural formulae correct.

H C O CH2CH3

b) propylethanoate or
O

CH3C O CH2CH2CH3

c) methyl butanoate or
O

CH3CH2CH2C OCH3

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