OCR A Level Chemistry

Topic Questions

6.9 Analytical Techniques

11 mark

The structure of 2-chloropropane is shown below.

2-chloropropane

Which description of the peaks in the 1H NMR spectrum of 2-chloropropane is correct?

  • 1 peak with a relative intensity of 6

  • 2 peaks with relative intensities of 3 : 4

  • 3 peaks with relative intensities of 3 : 1 : 3

  • 2 peaks with relative intensities 6 : 1

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21 mark

How many peaks will be shown in the low-resolution 1H NMR spectrum of propanal?

propanal

  • 2

  • 3

  • 4

  • 6

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31 mark

A suitable carrier gas for use in gas-liquid chromatography is:

  • Carbon dioxide

  • Chlorine

  • Nitrogen

  • Oxygen

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41 mark

In chromatography, which of the following can be the mobile phase?

  • Liquid only

  • Liquid or gas

  • Solid or liquid

  • Gas only

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51 mark

Primary alcohols can be oxidised to aldehydes.

Which statement shows the correct reagents and observations for this reaction?

 

Reagent 

Observation

A

Acidified silver nitrate solution

White precipitate forms

B

Fehling’s solution

Brick-red precipitate forms

C

Tollens’ reagent 

Silver mirror forms

D

Acidified potassium dichromate

Colour change from orange to green

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11 mark

Which statement is correct for the isomers of C6H10O2 below.

B33oX7Vy_cyclic-c6h10o2-isomers-inc-pyran-based

  • Both isomers produce 4 peaks in their 13C NMR spectrum

  • Both isomers effervesce with the addition of sodium hydrogen carbonate solution

  • One isomer produces a doublet with an integral of 3 in its 1H NMR spectrum

  • One isomer reacts with 2,4-dinitrophenylhydrazine to form an orange precipitate

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21 mark

A compound produces the 1H NMR spectrum below.

q5_21-1_ib_hl_medium_mcq

Which compound could have produced this spectrum?

  • CH3CH2OCH2CH3

  • CH3CH(OH)CH2CH3

  • CH3COCH2CH3

  • CH3COCH2CH2CH3

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31 mark

A compound produces the 13C NMR spectrum below.

ocr-a2-6-9-q11-2-methyl-3-pentanone-13c-nmr-spectrum

Which compound could have produced this spectrum?

  • CH3CH2COCH(CH3)2 

  • CH3CH2CH(OH)CH(CH3)2 

  • CH3CH2COCH2CH3 

  • CH3CH2COC(CH3)3 

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4
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1 mark

Which statement(s) is / are true about pentan-3-one?

  1. It will have a triplet and a quartet in its 1H NMR spectrum.
  2. It will create mass spectra peaks at 87 m / z and 57 m / z.
  3. It has a composition of 66.6 % carbon, 22.1 % oxygen and 11.2 % hydrogen.

  • 1, 2 and 3

  • Only 1 and 2

  • Only 2 and 3

  • Only 1

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51 mark

The monomer used to make perspex is methyl methacrylate.

 7-10-h-q51-aqa-al-chemistry

The 13C NMR spectrum of methyl methacrylate is show below

 7-10-h-q52-aqa-al-chemistry

 

What is the correct identity of the carbon labelled in peak 3?

  • -C-CH3

  • -COOCH3

  • -O-CH3

  • =C-CH3

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1
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1 mark

A chromatogram of two compounds, A and B, is shown.

tlc-exam-question

What is the Rf value of compound B?

  • 0.21

  • 0.44

  • 0.65

  • 1.54

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21 mark

Which of the following do components with a high Rf value have a greater affinity for?

  • No phase

  • The mobile phase

  • The stationary phase

  • The latent phase

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31 mark

Which statement(s) is / are correct for gas chromatography?

  1. The relative peak areas give the proportions of components in a mixture.
  2. The components in a mixture can be identified from their retention time.
  3. The components in a mixture are separated by their force of attraction to the liquid phase.
  • 1, 2 and 3

  • Only 1 and 2

  • Only 2 and 3

  • Only 1

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41 mark

Functional group analysis is performed on E-4-chloropen-2-ene below.

2e-4-chloro-2-pentene-skeletal

Which statement(s) is / are correct about the chemical tests performed?

  1. Warming with silver nitrate and ethanol will form a white precipitate
  2. Bromine water will change from orange to green
  3. Warming with Tollens' reagent will form a silver mirror
  • 1, 2 and 3

  • Only 1 and 2

  • Only 2 and 3

  • Only 1 

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51 mark

Which chemical test and observation for 2-oxobutanol is correct?

2-oxobutanol

  Chemical test Observation
A Add aqueous sodium carbonate Effervescence
B Add 2,4-dinitrophenylhydrazine White precipitate
C Warm with acidified potassium dichromate Colour change from orange to green
D Warm with Tollens' reagent Silver mirror

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61 mark

The product formed from an analytical test using bromine is shown below.

246-tribromophenol

Which chemical was tested for using bromine?

  • Benzoic acid

  • 2,5-Cyclohexadiene-1-ol

  • 4-Hydroxybenzoic acid

  • Phenol

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71 mark

Which description of the splitting pattern observed on the 1H NMR spectrum for organic compound is correct?

ocr-6-9m-q7

  • One doublet and four triplets

  • One triplet, one quartet and one singlet

  • One triplet, one doublet and three singlets

  • One triplet, one quartet and three singlets

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81 mark

Which compound is used as a standard in NMR chemical shift measurements?

  • D2O

  • CD3OD

  • DMSO

  • Si(CH3)4 

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