Download Total marks available

Name: _______________________________________________
Halogenoalkanes Homework
Date:
Time: 1 minute
Total marks available: 49
Total marks achieved: ______
Questions
Q1.
A reaction mechanism is shown below.
The hydroxide ion is acting as
A
an electrophile.
B
a catalyst.
C
a free radical.
D
a nucleophile.
(Total for question = 1 mark)
Q2.
Samples of 1-chloropropane and 1-bromopropane are warmed with water containing dissolved silver
nitrate in the presence of ethanol. The 1-chloropropane reacts more slowly because
A
the C—Cl bond is more polar than the C—Br bond.
B
the C—Cl bond is stronger than the C—Br bond.
C
1-chloropropane is less soluble than 1-bromopropane.
D
1-chloropropane is a weaker oxidizing agent than 1-bromopropane.
(Total for Question = 1 mark)
Q3.
The reaction of the halogenoalkane, C2H5Cl, with alcoholic ammonia is
A nucleophilic substitution.
B electrophilic substitution.
C reduction.
D elimination.
(Total for question = 1 mark)
Q4.
The molecule shown above is 3-chloro-3-methylhexane. It reacts with hot, alcoholic potassium hydroxide
to produce a number of different alkenes. This reaction can be classified as
A
elimination.
B
oxidation.
C
reduction.
D
substitution.
(Total for question = 1 mark)
Q5.
Electrophiles are
A
electron pair donors that are attracted to regions of high electron density.
B
electron pair donors that are attracted to regions of low electron density.
C
electron pair acceptors that are attracted to regions of high electron density.
D
electron pair acceptors that are attracted to regions of low electron density.
(Total for question = 1 mark)
Q6.
Halogenoalkanes react slowly with water to form alcohols. The equation for the reaction is
RX + H2O → ROH + H+ + X−
The rate of this reaction for different halogenoalkanes was investigated using the apparatus below.
In one experiment, equal amounts of 1-chlorobutane, 1-bromobutane and 1-iodobutane were placed in
separate test tubes with 5 cm3 of ethanol. These test tubes were placed in the water bath together with a
test tube containing aqueous silver nitrate. After about 5 minutes, 1 cm3 of the silver nitrate solution was
added to each test tube containing a halogenoalkane and the time taken for a precipitate to form in each
test tube was noted. The temperature of the water bath was maintained at 50°C.
(i) Why is ethanol used as a solvent in this experiment?
(1)
.............................................................................................................................................
.............................................................................................................................................
(ii) Explain why the apparatus was left for 5 minutes before the silver nitrate was added.
(1)
.............................................................................................................................................
.............................................................................................................................................
(iii) Name the precipitate formed in the test tube containing 1-bromobutane and write an ionic equation
for the formation of this precipitate. State symbols are not required.
(2)
Precipitate
.............................................................................................................................................
Ionic equation
(iv) Predict the order (fastest first) in which the halogenoalkanes form precipitates.
Explain your answer.
(2)
Order
.............................................................................................................................................
.............................................................................................................................................
Explanation
.............................................................................................................................................
.............................................................................................................................................
.............................................................................................................................................
.............................................................................................................................................
Q7.
This question is about two halogenoalkanes, X and Y, which have the structures shown below.
(a) (i) Draw the skeletal formula of X.
(1)
(ii) Name Y.
(1)
.............................................................................................................................................
(iii) Write an equation for the reaction of X with an alcoholic solution of ammonia, and name the
organic product.
(2)
Name of product
.............................................................................................................................................
(iv) When Y is heated with an aqueous solution of potassium hydroxide, an alcohol is formed in a
two-step reaction. Write the mechanism for this reaction using 'curly arrows' where appropriate and
clearly showing the structure of the intermediate.
(3)
(v) When Y is heated with an alcoholic solution of potassium hydroxide, the alkene C4H8 is
formed. What type of reaction occurs to produce the alkene?
(1)
.............................................................................................................................................
(b) Separate ethanolic solutions of X and Y were warmed with water containing dissolved silver
nitrate. Describe what would be seen in each case, ignoring any differences in the rates of reaction.
(2)
Observation with X
.............................................................................................................................................
Observation with Y
.............................................................................................................................................
(c) The rates of hydrolysis of primary halogenoalkanes are affected by the strength of the bond
between the carbon and the halogen atom.
Is the C—Br bond weaker or stronger than the C—I bond? Explain why the bond strength differs.
(2)
.............................................................................................................................................
.............................................................................................................................................
.............................................................................................................................................
.............................................................................................................................................
(Total for question = 12 marks)
Q8.
1-bromobutane is classified as a primary halogenoalkane and is one of the four structural isomers with a
molecular formula C4H9Br.
Give the skeletal formula of the three isomers, other than 1-bromobutane, classifying the halogenoalkane
in each case.
(3)
Q9.
This is a question about halogenoalkanes.
(a) Halogenoalkanes can react with hydroxide ions in different ways depending on the conditions used.
Using 1-chloro-1-fluoroethane, CH3CHClF, as an example of a halogenoalkane, the following reaction
could occur in aqueous solution.
CH3CHClF + OH− → CH3CHOHF + Cl−
(i) Suggest why it is unlikely that the fluorine atom in CH3CHClF would be substituted by the
hydroxide ion.
(1)
.............................................................................................................................................
.............................................................................................................................................
*(ii) A student attempted to draw the reaction mechanism for the reaction in (a)(i), but made a total of
three errors.
Identify these errors and state how they should be corrected.
(3)
First error
.............................................................................................................................................
.............................................................................................................................................
.............................................................................................................................................
Second error
.............................................................................................................................................
.............................................................................................................................................
.............................................................................................................................................
Third error
.............................................................................................................................................
.............................................................................................................................................
.............................................................................................................................................
(iii) In hot alcoholic solution, a different reaction may occur between halogenoalkanes and hydroxide
ions.
Write the equation for the reaction between 1-chloro-1-fluoroethane, CH3CHClF, and hydroxide ions
in alcoholic solution.
(2)
(b) Chloroethane can be produced in various ways as shown below. Identify, by name or formula, the
reagent needed for each of these reactions.
(3)
(c) (i) Chloroethane will react with alcoholic ammonia initially to produce ethylamine. Complete the
equation for this reaction.
(1)
.............................. + NH3 → .............................. + ..............................
(ii) Name the type and mechanism of the reaction occurring in (c)(i).
(2)
.............................................................................................................................................
.............................................................................................................................................
(iii) What feature of the ammonia molecule enables the reaction in (c)(i) to take place?
(1)
.............................................................................................................................................
(iv) If aqueous ammonia was used in (c)(i), instead of alcoholic ammonia, suggest the identity of the
organic product that would be formed.
(1)
.............................................................................................................................................
(Total for question = 14 marks)