CHEMISTRY 2.5
An assessment for AS90309
Describe the structural formulae and reactions of compounds containing selected
organic functional groups.
Credits: Four
INSTRUCTIONS
Answer ALL questions.
© New Zealand Institute of Chemistry 2005
2
You are advised to spend 40 minutes answering these questions.
QUESTION ONE:
1
Names and functional groups
Complete the following table showing the structural formulae and IUPAC (systematic) names
for some organic compounds.
Structural formula
(a)
(b)
(c)
IUPAC name
CH3OH
CH3 CH2 CH CH3
Br
CH2 CH CH2Cl
(d)
ethanoic acid
(e)
propyne
(f)
ethyl butanoate
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3
QUESTION TWO:
1
2
Isomerism
Give the structural formulae and names of two structural isomers of C2H4Cl2.
Structural formula
Structural formula
Name_____________________
Name_____________________
Explain whether it is possible for C2H4Cl2 to form geometrical isomers
_____________________________________________________________________________
_____________________________________________________________________________
_____________________________________________________________________________
3
Give the structural formula and name of an isomer of CH3–O–CH3.
Structural formula
Name_____________________
QUESTION THREE
Organic products
Give the structural formula of the organic products for the following reactions.
1
CH3–CH3 + Br2
ultra-violet light
2
CH3 CH CH3
concentrated H2SO4
OH
3
4
CH3–CH=CH–CH3
KMnO4
Cr2O72–/H+
CH3–CH2–CH2–CH2–CH2OH +
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4
QUESTION FOUR:
1
Polymers
In the space below, draw a six-carbon section of the polymer formed from the monomer:
H
H
C C
H
QUESTION FIVE:
1
Cl
Reactions of alkenes
Draw the structural formula for and name the two possible organic products for the following
reaction.
CH3 CH CH2
+
H2O/H+
Name
Name
2
Circle the major product in part 1.
3
Discuss the structural requirements of the reactants that lead to two products being formed in
an addition reaction.
_____________________________________________________________________________
_____________________________________________________________________________
_____________________________________________________________________________
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5
QUESTION SIX:
1
Organic reactions
Bromine water is added to a sample of hexene in a test tube and the mixture is gently shaken,
then allowed to settle.
(a)
Write an equation for this reaction.
_____________________________________________________________________________
(b) Describe two observations that would be made when this reaction is carried out.
(i) ___________________________________________________________________________
(ii)___________________________________________________________________________
(c)
Give reasons for each of these observations in part (b)
Reason for observation (i) ________________________________________________________
_____________________________________________________________________________
Reason for observation (ii)________________________________________________________
_____________________________________________________________________________
2
(a)
Describe a chemical test that could be used to distinguish between ethanol and ethanoic
acid solution. Include the reagents needed, the observations that would be made for each
substance.
Reagents ______________________________________________________________________
Observations __________________________________________________________________
_____________________________________________________________________________
_____________________________________________________________________________
(b)
Give a reason for the different reactivities of the two substances with the chosen
reagent.
_____________________________________________________________________________
_____________________________________________________________________________
_____________________________________________________________________________
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6
QUESTION SEVEN
Preparation of an ester.
The ester methyl propanoate can be prepared by the following steps.
a
Mix 10 mL of methanol with 12 mL of propanoic acid in a large test tube.
b
Add 10 drops of concentrated sulfuric acid, stopper the test tube and leave over night.
c
Add 20 mL of water to the mixture in the test tube, shake gently and allow to settle.
d
Remove the upper ester layer from the test tube with a teat pipette (eye dropper) and
place in a 50 mL conical flask.
e
Add 20 mL of a saturated solution of sodium bicarbonate, (NaHCO3), to the ester in the
conical flask and gently shake.
f
Let the layers in the flask separate and remove the upper ester layer.
Questions
1
(a)
What is the main function of the concentrated sulfuric acid?
_____________________________________________________________________________
(b)
What is the function of the sodium bicarbonate?
_____________________________________________________________________________
2
Steps c and d are used to separate the ester from the reactants. Discuss how the properties of
the reactants and products make it possible to use this method to separate the ester.
_____________________________________________________________________________
_____________________________________________________________________________
_____________________________________________________________________________
3
Write a balanced equation, using structural formulae, for the preparation of the methyl
propanoate.
4
Describe one distinctive characteristic physical property the ester would have.
_____________________________________________________________________________
_____________________________________________________________________________
End of Assessment
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