Chlorine can be produced by the reaction of hydrogen chloride with air using the Deacon process. (a) (i) Using the potential energy diagram, determine the activation energy, in kJ mol -1 , for the forward reaction. (ii) Explain why increasing the temperature in the Deacon process results in less chlorine being produced. (b) One laboratory method for the preparation of chlorine gas involves adding concentrated hydrochloric acid to potassium permanganate. The chlorine gas produced also contains small amounts of hydrogen chloride gas. To remove the hydrogen chloride gas the gases are bubbled through water. Finally, insoluble chlorine gas is collected. Complete a labelled diagram to show an apparatus suitable for carrying out this preparation. (c) Carbon tetrachloride, CCl 4 , is prepared by the reaction of chlorine gas, Cl 2 , with methane, CH 4 . Calculate the enthalpy change, in kJ mol -1 , for this reaction using the following information. C 2 + 2H 2 → CH 4 ΔH = -75 kJ mol -1 CCl 2 + Cl 2 → CCl 4 ΔH = -98 kJ mol -1 2HCl(g) + Cl 2 → HCl(g) ΔH = -92 kJ mol -1

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Chlorine can be produced by the reaction of hydrogen chloride with air using the Deacon process - Scottish Highers Chemistry - Question 9 - 2019

Question 9

Chlorine can be produced by the reaction of hydrogen chloride with air using the Deacon process. (a) (i) Using the potential energy diagram, determine the activatio... show full transcript

Worked Solution & Example Answer:Chlorine can be produced by the reaction of hydrogen chloride with air using the Deacon process - Scottish Highers Chemistry - Question 9 - 2019

Step 1

Using the potential energy diagram, determine the activation energy, in kJ mol-1, for the forward reaction.

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Answer

The activation energy for the forward reaction can be determined by finding the difference in potential energy between the reactants and the peak of the energy barrier in the potential energy diagram. If the potential energy of the reactants is approximately -50 kJ mol-1 and the peak is +220 kJ mol-1, then:

$ext{Activation energy} = 220 - (-50) = 270 ext{ kJ mol}^{-1}$

Step 2

Explain why increasing the temperature in the Deacon process results in less chlorine being produced.

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Answer

Increasing the temperature favors the endothermic (reverse) reaction according to Le Chatelier's principle. In the Deacon process, the forward reaction is exothermic, meaning that raising the temperature shifts the equilibrium position towards the left, thereby reducing the production of chlorine gas.

Step 3

Complete a labelled diagram to show an apparatus suitable for carrying out this preparation.

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Answer

A suitable apparatus for the preparation of chlorine gas would include:

A flask containing concentrated hydrochloric acid connected to a delivery tube.
A container or water bath to bubble the gas through water, where hydrogen chloride gas is dissolved.
A separate collecting vessel to capture the insoluble chlorine gas.

[Diagram not included in this text]
Label the delivery tube, the flask with concentrated hydrochloric acid, the water bath, and the collection vessel.

Step 4

Calculate the enthalpy change, in kJ mol-1, for this reaction using the following information.

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Answer

To calculate the overall enthalpy change for the reaction producing carbon tetrachloride (CCl4) from chlorine gas (Cl2) and methane (CH4):

Write the enthalpy change equation: $ext{ΔH} = [ ext{ΔH}_{CCl_4}] + [ ext{ΔH}_{CH_4}] + [ ext{ΔH}_{HCl}]$
Substitute the values:
- For the formation of CCl4: $ext{ΔH} = -98 ext{ kJ mol}^{-1}$
- For the reaction of CH4: $ext{ΔH} = -75 ext{ kJ mol}^{-1}$
- For the formation of HCl: $ext{ΔH} = 2 imes -92 ext{ kJ mol}^{-1}$
Add these values: $ext{Total ΔH} = -98 + (-75) + 2 imes (-92)$
$= -391 ext{ kJ mol}^{-1}$

Thus, the overall enthalpy change for the reaction is -391 kJ mol-1.

Chlorine can be produced by the reaction of hydrogen chloride with air using the Deacon process - Scottish Highers Chemistry - Question 9 - 2019

Worked Solution & Example Answer:Chlorine can be produced by the reaction of hydrogen chloride with air using the Deacon process - Scottish Highers Chemistry - Question 9 - 2019

Using the potential energy diagram, determine the activation energy, in kJ mol<sup>-1</sup>, for the forward reaction.

Explain why increasing the temperature in the Deacon process results in less chlorine being produced.

Complete a labelled diagram to show an apparatus suitable for carrying out this preparation.

Calculate the enthalpy change, in kJ mol<sup>-1</sup>, for this reaction using the following information.

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