International A LevelChemistryEdexcelExam Questions2. Energetics, Group Chemistry, Halogenoalkanes and Alcohols2.10 Organic Chemistry: Techniques & Spectra

Organic Chemistry: Techniques & Spectra (Edexcel International A Level Chemistry)

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2.10 Organic Chemistry: Techniques & Spectra

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2.10 Organic Chemistry: Techniques & Spectra

1a
Sme Calculator7 marks

This question is about two organic compounds, X and Y. Both are liquids which contain carbon, hydrogen and oxygen only.

The mass of hydrogen and of carbon present in 1.33 g of X were determined by passing its combustion products through the apparatus shown.

q2a-paper-3-jan-2022-edexcel-ial-chemistry
i)
State the measurements that should be made.

(2)

ii)
Give two reasons why pure O2 (g), and not air, should be used.

(2)

iii)

The experiment showed that 1.33 g of X contains 0.14 g of hydrogen and 0.63 g of carbon.

Calculate the empirical formula of X, using these data.
You must show your working.

(3)

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1b1 mark

When phosphorus(V) chloride is added to X, steamy white fumes are seen.

State what can be deduced about compound X from this observation only.

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1c3 marks

Compound X is converted into compound Y when refluxed with excess sodium dichromate(VI) in sulfuric acid.

Compound Y is a liquid that is soluble in the reaction mixture.

Draw a labelled diagram of the apparatus that could be used to separate Y from the reaction mixture.

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1d2 marks

The infrared spectrum of Y is shown.

q2d-paper-3-jan-2022-edexcel-ial-chemistry

The table shows some infrared absorption data.

Bond Wavenumber range / cm–1
C—H (alkane) 2962–2853
O—H (alcohols and phenols) 3750–3200
O—H (carboxylic acids) 3300–2500
CequalsC (alkene) 1669–1645
C equalsO (aldehydes, ketones, carboxylic acids) 1740–1680

Explain how this spectrum shows that Y contains a carboxylic acid functional group, quoting data from the table.

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1e
Sme Calculator2 marks

The mass spectrum of Y is shown.

q2e-paper-3-jan-2022-edexcel-ial-chemistry
i)
Show that the mass spectrum is consistent with Y having the molecular formula C3H4O3 .

(1)

ii)

Suggest the structure of the ion causing the peak at m / z = 43 in the mass spectrum of Y.

(1)

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1f
Sme Calculator2 marks

Compound X contains one type of functional group.

Compound Y contains two different functional groups.

Use the information in the question to deduce the structures of X and Y.

Compound X

Compound Y

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2a4 marks

Geraniol is used in perfumes and can be extracted from many plants.

Data on geraniol are shown.

Solubility in water Melting
temperature/°C		 Boiling
temperature/°C		 Density / g cm−3
insoluble −15 230 0.889


The structure of geraniol is shown.

geraniol

Geraniol has two different types of functional group.

Name the functional groups, giving a chemical test and its positive result to show the presence of each group.

First functional group: 

Second functional group: 

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2b3 marks

Geraniol is extracted by steam distillation.

q2b-paper-3-oct-2021-edexcel-ial-chemistry

The steam distillation product is geraniol and water. The water may contain dissolved impurities which have similar boiling temperatures to geraniol.

The contents of the collecting flask are transferred to a piece of apparatus used to separate the geraniol from the water layer.

Draw a labelled diagram of this apparatus and its contents.

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2c3 marks

The geraniol will still contain small quantities of water.

Describe how to produce a sample of pure, dry geraniol using a named drying agent.

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2d3 marks

The hazard labels for pure geraniol are shown.

q2d-paper-3-oct-2021-edexcel-ial-chemistry
i)
Complete the table to identify the hazards indicated by the symbols.

(2)

ii)

State one precaution, other than wearing safety spectacles and a laboratory coat, that should be taken when using pure geraniol to reduce the risk associated with the hazard symbol shown.

q2d-2-paper-3-oct-2021-edexcel-ial-chemistry

(1)

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2e1 mark

State the appearance of the flame when geraniol is ignited.

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2f2 marks

Geraniol reacts with excess hydrogen gas.

i)
State the essential condition required for this reaction.

(1)

ii)
Draw the skeletal formula of the product of this reaction.

(1)

q2f-paper-3-oct-2021-edexcel-ial-chemistry

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3a2 marks

Phosgene (COCl2) is a colourless gas used in the pharmaceutical industry.
Phosgene has a boiling temperature of 8 °C and is extremely toxic.

Complete the dot-and-cross diagram to show the bonding in phosgene.

q22a-paper-2-june-2021-edexcel-ial-chemistry

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3b
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Phosgene can be formed from carbon monoxide and chlorine, using a catalyst of activated carbon.

CO (g) + Cl2 (g) ⇌ COCl2 (g)           ΔrH = –107.6 kJ mol–1

i)
State and explain how the reaction conditions could be changed to maximise the equilibrium yield of phosgene in this reaction.

(4)

ii)

The standard enthalpy change of formation for phosgene is ΔfH = –220.1 kJ mol–1.

Complete the Hess cycle and determine the standard enthalpy change of formation for carbon monoxide. Use the data from (b)(i).

Include state symbols in your cycle.

(4)

CO(g) + Cl2 (g) → COCl2 (g)

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3c
Sme Calculator4 marks

The mass spectrum of a sample of phosgene is shown.

The peak at m / z = 65 has been omitted.

q22c-paper-2-june-2021-edexcel-ial-chemistry
i)
Give the reason for the ratio of peak heights at m / z values of 102, 100 and 98

(2)

ii)
Suggest an identity for the peak at m / z = 63.

(1)

iii)
The peak at m / z = 65 has been omitted.

Draw on the mass spectrum the peak at m / z = 65, showing its relative intensity.

(1)

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3d2 marks

Use your Data Booklet to suggest the wavenumber of a strong absorbance you would expect to see in the infrared spectrum for phosgene. Justify your answer.

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3e4 marks

In UV light, trichloromethane (CHCl3, boiling temperature 61 °C) reacts with oxygen to form phosgene and hydrogen chloride.

i)

Write an equation for this reaction.
State symbols are not required.

(1)

ii)

In a closed bottle, the rate of this reaction decreases with time.

Give a reason for this.

(1)

iii)

Suggest a precaution that should be taken when opening a bottle of trichloromethane.

(1)

iv)
Trichloromethane can be used as an anaesthetic.

Suggest whether an old bottle of trichloromethane can still be used for medical treatment, giving a reason for your answer.

(1)

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