3
© OCR 2025 Turn over
1
, 2
This question is about reactions of haloalkanes.
(a) CH3Cl is made by plants that grow on marshes.
If CH3Cl reaches the stratosphere, electromagnetic radiation causes it to undergo homolytic fission
forming chlorine radicals.
(i) Give the systematic name of CH3Cl .
. ....................................................................................................................................................................................................... [1]
(ii) Draw ‘half curly arrows’ to show the mechanism of the homolytic fission of CH3Cl .
Show the products of the reaction.
H
H C Cl
H
[2]
(iii) Which type of electromagnetic radiation causes this homolytic fission to occur in the stratosphere?
. ....................................................................................................................................................................................................... [1]
(iv) The bond energy of the C–Cl bond is 346 kJ mol–1.
Calculate the wavelength (in m) of radiation which breaks this bond. Give
your answer to an appropriate number of significant figures.
Wavelength = ..................................................... m [5]
(v) Chlorine radicals catalyse the breakdown of ozone in the stratosphere.
Write equations to show how this occurs and give the overall equation.
Overall equation:
[2]
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(vi) Why is the breakdown of ozone in the stratosphere harmful to humans?
..........................................................................................................................................................
..........................................................................................................................................................
. ....................................................................................................................................................................................................... [2]
(b) CH3Cl reacts with ammonia to give an amine salt.
CH3Cl + NH3 CH3NH3Cl Equation 1.1
Ammonia is acting as a nucleophile here.
(i) Explain what is meant by the term nucleophile.
..........................................................................................................................................................
. ....................................................................................................................................................................................................... [1]
(ii) Show the mechanism of Equation 1.1.
Use curly arrows and show relevant lone pairs and the ionic products.
H
H C Cl
H
H N H
H
[2]
(iii) The product of Equation 1.1 is a salt of CH3NH2.
Give the systematic name for CH3NH2.
. ....................................................................................................................................................................................................... [1]
(c) The reaction between a haloalkane and hydroxide ions is a nucleophilic substitution reaction.
A student reacts 1-chlorobutane, 1-bromobutane and 1-iodobutane separately with aqueous
sodium hydroxide.
Which will react fastest and why?
..........................................................................................................................................................
..........................................................................................................................................................
. ....................................................................................................................................................................................................... [2]
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2 Some students study the nitrogen compounds in the soil.
(a) How many neutrons are in an atom of 14N?
. ....................................................................................................................................................................................................... [1]
(b) The students make ammonia from a fertiliser containing NH + 4ions.
Identify the reagent that they use.
. ....................................................................................................................................................................................................... [1]
(c) The students add an aqueous solution of ammonia to a solution of FeSO4. A
precipitate forms.
Give the colour of the precipitate and write an ionic equation for its formation. Include
state symbols.
Colour: ..............................................................................................................................................
Ionic equation:
[3]
(d) The students read that ammonium ions are oxidised to NO – by
2 bacteria in the soil.
(i) Give the systematic name of NO –. 2
. ....................................................................................................................................................................................................... [1]
(ii) The students add acid to NaNO2(s) in a test tube.
A colourless gas A (with nitrogen in the +2 oxidation state) and NO – ions
3 are produced.
Gas A turns to a brown gas B at the top of the test tube. Suggest
the formula of the brown gas B.
Suggest an ionic equation for the formation of gas A from acidified NO – ions.
2
Formula of brown gas B: ..................................................................................................................
Ionic equation:
[3]
© OCR 2025
© OCR 2025 Turn over
1
, 2
This question is about reactions of haloalkanes.
(a) CH3Cl is made by plants that grow on marshes.
If CH3Cl reaches the stratosphere, electromagnetic radiation causes it to undergo homolytic fission
forming chlorine radicals.
(i) Give the systematic name of CH3Cl .
. ....................................................................................................................................................................................................... [1]
(ii) Draw ‘half curly arrows’ to show the mechanism of the homolytic fission of CH3Cl .
Show the products of the reaction.
H
H C Cl
H
[2]
(iii) Which type of electromagnetic radiation causes this homolytic fission to occur in the stratosphere?
. ....................................................................................................................................................................................................... [1]
(iv) The bond energy of the C–Cl bond is 346 kJ mol–1.
Calculate the wavelength (in m) of radiation which breaks this bond. Give
your answer to an appropriate number of significant figures.
Wavelength = ..................................................... m [5]
(v) Chlorine radicals catalyse the breakdown of ozone in the stratosphere.
Write equations to show how this occurs and give the overall equation.
Overall equation:
[2]
© OCR 2025
, 3
(vi) Why is the breakdown of ozone in the stratosphere harmful to humans?
..........................................................................................................................................................
..........................................................................................................................................................
. ....................................................................................................................................................................................................... [2]
(b) CH3Cl reacts with ammonia to give an amine salt.
CH3Cl + NH3 CH3NH3Cl Equation 1.1
Ammonia is acting as a nucleophile here.
(i) Explain what is meant by the term nucleophile.
..........................................................................................................................................................
. ....................................................................................................................................................................................................... [1]
(ii) Show the mechanism of Equation 1.1.
Use curly arrows and show relevant lone pairs and the ionic products.
H
H C Cl
H
H N H
H
[2]
(iii) The product of Equation 1.1 is a salt of CH3NH2.
Give the systematic name for CH3NH2.
. ....................................................................................................................................................................................................... [1]
(c) The reaction between a haloalkane and hydroxide ions is a nucleophilic substitution reaction.
A student reacts 1-chlorobutane, 1-bromobutane and 1-iodobutane separately with aqueous
sodium hydroxide.
Which will react fastest and why?
..........................................................................................................................................................
..........................................................................................................................................................
. ....................................................................................................................................................................................................... [2]
© OCR 2025 Turn over
, 4
2 Some students study the nitrogen compounds in the soil.
(a) How many neutrons are in an atom of 14N?
. ....................................................................................................................................................................................................... [1]
(b) The students make ammonia from a fertiliser containing NH + 4ions.
Identify the reagent that they use.
. ....................................................................................................................................................................................................... [1]
(c) The students add an aqueous solution of ammonia to a solution of FeSO4. A
precipitate forms.
Give the colour of the precipitate and write an ionic equation for its formation. Include
state symbols.
Colour: ..............................................................................................................................................
Ionic equation:
[3]
(d) The students read that ammonium ions are oxidised to NO – by
2 bacteria in the soil.
(i) Give the systematic name of NO –. 2
. ....................................................................................................................................................................................................... [1]
(ii) The students add acid to NaNO2(s) in a test tube.
A colourless gas A (with nitrogen in the +2 oxidation state) and NO – ions
3 are produced.
Gas A turns to a brown gas B at the top of the test tube. Suggest
the formula of the brown gas B.
Suggest an ionic equation for the formation of gas A from acidified NO – ions.
2
Formula of brown gas B: ..................................................................................................................
Ionic equation:
[3]
© OCR 2025
