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NAME _____________________________________________________
CLASS ____________________
DUE DATE ____________________
SCHOOL
ASSIGNMENT SUB TOPIC 5.3: ALCOHOLS
Why have laws been introduced to prevent drink driving? Drinking
alcohol impairs judgement, reducesvigilance, slows reaction times
and increases the effect of tunnel vision. The inability to see
what is happeningon either side when looking straight ahead is
called tunnel vision. With alcohol in the blood, sight angle
isdiminished. This lack of vision causes collisions, with their
tragic consequences, even though you may wellask, Why did they not
see this vehicle? The answer is that they did not! If you drink,
dont drive.
1. Alcohols are organic compounds with anOH group. It is called
a hydroxyl group, not a hydroxide group. Why?
_______________________________________________________________________________
(1)
2. (a) Give systematic names for these alcohols:
(i) CH3 CH2 CH2 CH2 OH
________________________________________________
(ii) CH3 CH2 CHOH
CH3 ________________________________________________
CH3
(iii) CH3 CH2 CHCH2 OH ______________________________________
(3)
(b) Classify each as a primary, secondary or tertiary
alcohol.
_________________________________________________________________________________________
_______________________________________________________________________________
(3)
3. Like water, alcohols are capable of intermolecular hydrogen
bonding.
(a) What does this statement mean?
_______________________________________________________________________________
(1)
(b) What properties does the ability to hydrogen bond give to a
compound?
_________________________________________________________________________________________
_________________________________________________________________________________________
_______________________________________________________________________________
(2)
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4. (a) Glucose solution was fermented underanaerobicconditions.
The glucose solution was boiled and thencooled before the yeast was
added.
(i) Why was the glucose solution boiled and then cooled before
the yeast was added?
____________________________________________________________________________________
___________________________________________________________________________
(1)
(ii) What does anaerobicmean?
____________________________________________________________________________________
___________________________________________________________________________
(1)
(iii) Give one expected observation during the fermentation.
___________________________________________________________________________
(1)
(iv) Give one use of ethanol, apart from alcoholic drinks.
___________________________________________________________________________
(1)
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5. Ethanol is the starting material for a range of important
organic chemicals. The reactions, which produce some ofthese, are
summarised below. The reagents and conditions for the reactions
have not been included.
CH3CO2C2H5 CH3CHO
A B
C2H5OH CH3CO2HC
State the reagents and conditions needed to bring about each of
the reactions A to C above.
A
____________________________________________________________________________________
____________________________________________________________________________________
B
____________________________________________________________________________________
____________________________________________________________________________________
C
____________________________________________________________________________________
___________________________________________________________________________
(6)
6. Propan-1-ol, C3H7OH, is refluxed with an acidified solution
of potassium dichromate (VI) to produce propanoic acid.The
acidified potassium dichromate (VI) acts as an oxidising agent.
(a) Explain what is meant by the term reflux.
________________________________________________________________________________________
_______________________________________________________________________________
(1)
(b) State what colour change takes place in the reaction
mixture.
from ___________________________ to ____________________________
(2)
(c) Write a balanced equation for the oxidation of propan-1-ol
to propanoic acid. The oxidising agent can berepresented as [O] in
your equation.
_______________________________________________________________________________
(2)
Student note:
This graph shows the increase in the chances of having an
accident with a person driving with increasinglevels of alcohol in
the blood. Can you suggest why 0.05 % (50 mg/100mL) is taken for
the legal limit?
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7. Ethanol is a very important material in the chemical industry
and to the wine industry. It is made by two majorprocesses the
fermentation of grape sugar and the hydration of ethene.
(a) Outline the fermentation method for producing ethanol.
_________________________________________________________________________________________
_________________________________________________________________________________________
_________________________________________________________________________________________
_________________________________________________________________________________________
_______________________________________________________________________________
(3)
(b) Why does fermentation produce a maximum concentration of
ethanol of no more than 15%?
_________________________________________________________________________________________
_______________________________________________________________________________
(1)
(c) The product of fermentation consists of aqueous ethanol
which contains a solid material. Suggest what thissolid could
be.
_______________________________________________________________________________
(1)
(d) In the hydration method, ethene and steam are passed over a
catalyst, at about 350C and 60 atm pressure.This produces a
conversion of about 8% per pass, with the unreacted gases being
recycled.
(i) Why is a catalyst used?
____________________________________________________________________________________
(ii) What is the source of the large amounts of ethene
required?
___________________________________________________________________________
(2)
8. The production of body odour often begins with secretions
from glands called apocrine glands which are mostnumerous in the
armpits. Skin bacteria, which live in the armpits, use these
secretions to produce energy andmany different waste products.
Scientists have isolated one of these products, compound E, which
is shown below.Compound E can be oxidised to form compounds F and
G.
(a) Compound E contains two functional groups. Identify both
functional groups and state how you could test foreach.
Functional group 1
________________________________________________________________
Test
________________________________________________________________
Observation
________________________________________________________________
Functional group 2
________________________________________________________________
Test
________________________________________________________________
Observation
_______________________________________________________ (6)
(b) Suggest the structural formula of compound F.
(1)
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9. Compound A is an alcohol, which has several structural
isomers.
(a) Analysis of A shows that it contains 68.2% carbon and 13.6%
hydrogen, by mass. Show that this informationis consistent with an
empirical formula of C5H12O for A.
(3)
(b) The empirical formula of A is also its molecular formula.
Give the structural formula of an isomer of C5H12Owhich is:
(i) a primary alcohol;
(ii) a secondary alcohol which has a branched carbon chain;
(iii) a tertiary alcohol.
(3)
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(c) Each of these alcohols reacts differently with a solution of
potassium dichromate (VI) which has been acidifiedwith sulfuric
acid. For each example in (b), give the structure of the organic
product from this treatment. Ifthere is no product, say so.
(i) from the primary alcohol
(ii) from the secondary alcohol
(iii) from the tertiary alcohol
(3)
10. Before the introduction of infra-red (IR) spectroscopy to
determine blood alcohol content of drivers, gas
liquidchromatography (GLC) was used.
The chromatogram shown gives the results of a GLC analysis of
the first five straight chained primary alcohols. Themore volatile
a compound the less its retention time.
(a) Record, in table form, the name, the formula and retention
time for each alcohol analysed.
_________________________________________________________________________________________
_________________________________________________________________________________________
_________________________________________________________________________________________
_________________________________________________________________________________________
_______________________________________________________________________________
(5)
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(b) Estimate a retention time for hexan-1-ol
_______________________________________________________________________________
(1)
In GLC analysis for BAC a doctor takes a blood sample and an
exact amount of blood is mixed with a knownamount of a standard
solution of propan-1-ol. Here is a chromatogram from such an
analysis.
(c) What is meant by the term, a standard solution?
_________________________________________________________________________________________
_______________________________________________________________________________
(2)
(d) Why is a standard amount of propan-1-ol added to the
blood?
_________________________________________________________________________________________
_________________________________________________________________________________________
_________________________________________________________________________________________
_______________________________________________________________________________
(3)
(c) If the concentration of the propan-1-ol was 60 mg per 100 mL
of solution should the driver be charged for drinkdriving? Why is a
simple yes or no not a sufficient answer?
_________________________________________________________________________________________
_________________________________________________________________________________________
_________________________________________________________________________________________
_______________________________________________________________________________
(3)
Student note:
In roadside random breath testing the police use fuel cells. At
one electrode the alcohol in the breath(which is in direct
proportion to the amount consumed) is oxidized to ethanoic acid,
while at the otherelectrode oxygen is reduced to water. The higher
the concentration of alcohol in the breath, the higher thevoltage
of the cell.
If the reading shows close to the limit, or over the limit
(0.05%), then the suspect is taken to a police stationfor a more
accurate determination of blood alcohol concentration, using an
infra-red absorptionspectrometer.
A blood sample analysis, using gas-liquid chromatography, can
give an even more accurate result.
These tests must be carried out within a time limit, usually
under two hours, as the body will remove
alcohol at the rate of 0.01% per hour.
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11. Various methods have been used to determine whether a driver
of a motor vehicle has a blood alcoholconcentration (BAC) in excess
of the legal limit (50 mg per 100 mL of blood).
(a) The earliest method for detecting ethanol in breath was
based on a reaction that produced a colour change:orange dichromate
(VI) ions react with ethanol to form green chromium (III) ions.
(i) Give the structural formulae of two organic products that
could be formed from ethanol by reaction withacidified dichromate
(VI) ions.
(2)
(ii) Write a balanced half-equation for the conversion of
dichromate (VI) ions, Cr2O72-
(aq), into chromium (III)ions, Cr
3+(aq), in acid solution. What type of reaction is
occurring?
___________________________________________________________________________
(2)
(b) Another way of finding ethanol concentration in breath is by
using an electrochemical cell containing aphosphoric acid solution.
At one electrode oxygen is reduced to water, whilst at the other
ethanol is oxidisedto ethanoic acid.
(i) Explain how measuring the ethanol concentration in breath
can lead to a reliable estimation of itsconcentration in blood.
____________________________________________________________________________________
____________________________________________________________________________________
____________________________________________________________________________________
___________________________________________________________________________
(3)
(ii) Write a balanced half-equation for the reaction occurring
at the electrode where oxidation occurs.
___________________________________________________________________________
(2)
Total /71
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ANSWERS SUB TOPIC 5.3: ALCHOHOLS
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