Topic questions Chemical analysis Tests for organic functional groups
14 questions · 153 marks · about 3.5 hours
The structure of vitamin C is shown.
Which reagent(s) will react with vitamin C?
1 Aqueous bromine water
2 Acidified potassium dichromate(VI)
3 Aqueous silver nitrate in ethanol
A 1, 2 and 3
B Only 1 and 2
C Only 2 and 3
D Only 1
This question is about carbonyl compounds.
The three compounds below each contain a ketone and one other functional group.
Pyruvic acid
Methylglyoxal
Acetol
What is a functional group ?
A chemical test is carried out which gives a positive result for all three compounds.
Suggest the reagent and observation of this chemical test.
Reagent........
Observation........
A student is provided with three unlabelled sample tubes, containing either pyruvic acid, methylglyoxal or acetol.
The student carries out three chemical tests on each sample.
Complete the table with the expected observations, including ‘no change’ where appropriate.
Complete the flowchart for the reactions of pyruvic acid.
Geraniol, shown below, is a component in many natural oils.
Which pair of reagents identifies both functional groups in geraniol?
A Acidified dichromate(VI) and 2,4-dinitrophenylhydrazine.
B Bromine water and 2,4-dinitrophenylhydrazine.
C Bromine water and acidified dichromate(VI).
D Tollens’ reagent and aqueous silver nitrate in ethanol.
This question is about the analysis of organic compounds.
Determine the Rf value of propan-1-ol.
Show your working.
Write an equation for the alkaline hydrolysis of 1-bromopropane.
Show structures of organic compounds.
A student investigates the alkaline hydrolysis of 1-chloropropane using the same method as for 1-bromopropane.
Predict, with reasons, how the appearance of the reaction mixture in the chromatogram produced after 20 minutes would be different when 1-chloropropane is used instead of 1-bromopropane.
Suggest why propan-1-ol is run alongside the reaction mixture.
Write the formula of the species causing the colours after refluxing with acidified dichromate(VI
Green solution........
Orange solution........
* The student is provided with further information about compounds F– I.
• They all have the molecular formula C5H10O.
• One of the compounds is alicyclic.
• The other compounds are unbranched.
Use this further information and the student’s observations in Table 5.1 to answer the following.
• How do the observations provide evidence for the possible functional groups in compounds F– I ?
• Suggest a possible structure for each of the compounds F– I.
Show your reasoning.
Which compound reacts with 2,4-dinitrophenylhydrazine but does not react with Tollens’ reagent?
A C6H5COCOOH
B C6H5CH(OH)CHO
C CH3COCHO
D CH3CH2CH(OH)CH3
23* An unknown organic compound is analysed.
The results are shown below.
Addition of 2,4-DNP No visible change
Elemental analysis by mass C, 66.63%; H, 11.18%; O, 22.19%
Mass spectrum Molecular ion peak at m / z = 144.0
IR spectrum
Proton NMR spectrum The numbers by each peak are the relative peak areas.
Use the information to identify the organic compound.
Show all your reasoning.
This question is about carbonyl compounds.
Describe a chemical test to confirm the presence of a carbonyl group.
How could the product of this test be used to identify the carbonyl compound?
Your answer should not include spectroscopy.
Describe a chemical test that would identify whether a carbonyl compound is an aldehyde.
Your answer should include the reagent and observations.
A student is provided with two unknown carbonyl compounds, F and G.
The compounds are analysed and found to have identical percentage compositions by mass: C: 62.07%; H: 10.34%; O: 27.59%
The mass spectra of the two compounds are shown below.
Use the results to identify the structures of the two compounds.
Include relevant peaks present in the mass spectrum of each compound.
This question is about the chemistry of aromatic compounds.
What chemical test(s) could be used to confirm the presence of the phenol group in compounds K and L ?
A student thought that13C NMR spectroscopy could be used to distinguish between compounds J, K and L.
Explain, with reasoning, whether the student is correct.
Compound J is substituted at the 2-and 4-positions by chlorine in the presence of a catalyst.
Outline the mechanism for the 4 substitution of compound J by chlorine in the presence of a catalyst.
Show the role of the catalyst.
Compounds K and L react with chlorine much more readily than compound J.
Explain why.
Compound J, C6H5CH2CH2OH, is reacted with acidified potassium dichromate(VI) under reflux to form organic product M.
Write an equation for this reaction.
Use [O] to represent the oxidising agent and show the structure of M.
A two-stage synthesis of an amine from compound J is shown below.
Add the reagents for each stage of this synthesis.
Compound J
21* Compounds D, E and F are isomers with the molecular formula C5H10O. One of the compounds is alicyclic.
A student carries out test-tube tests on the compounds. The observations are shown below.
13C NMR spectrum of D
Compound D has 3 peaks at 
/ ppm: 24, 36, 73.
1H NMR spectra of E and F The integration data has been omitted.
Compound E
Compound F
Analyse the observations and results to identify the structures of D, E and F.
Explain your reasoning.
The carbonyl compounds, F and G, shown below, contribute to the flavour of coffee.
Compound F is a member of a homologous series.
Explain the term homologous series.
Predict the molecular formula for the member of this homologous series containing 24 carbon atoms.
Describe suitable chemical tests, with observations, that would confirm the presence of the functional groups in F and G.
Explain why the mechanism in (c)(i) involves heterolytic fission.
This question is about unsaturated aldehydes and alcohols.
Outline the reaction mechanism for the formation of one of the organic products.
Include curly arrows and relevant dipoles.
Explain why one of the organic products forms in a much greater quantity than the other organic product.
Describe how the observations from a chemical test would distinguish between geraniol and citronellal.
What is the molecular formula of geraniol?
Explain why geraniol and citronellal are structural isomers of each other.
Explain the term stereoisomerism.
Dettol ® is a disinfectant containing the antiseptic chloroxylenol, shown below.
Chloroxylenol is a weak Brønsted–Lowry acid.
What is the systematic name of chloroxylenol?
Predict the number of peaks in a13C NMR spectrum of chloroxylenol.
Name the functional group responsible for the acidity of chloroxylenol and describe a simple test which would confirm the presence of this group.
Functional group........
Test........
A student measures the pH of the contents in a bottle of Dettol ® as 5.14.
The label on the bottle shows the percentage of chloroxylenol in Dettol ® as 4.80% i.e. 100 cm3 of Dettol® contains 4.80 g of chloroxylenol.
Assume the following:
• Chloroxylenol is the only acidic component in Dettol ®.
• Chloroxylenol is a weak monobasic acid.
• The density of Dettol ® is 1.00 g cm −3.
Write the equation, using molecular formulae, for the acid dissociation of chloroxylenol.
Calculate the acid dissociation constant, Ka, for chloroxylenol.
Ka =........ mol dm−3
Dettol® contains other chemicals including 
-terpineol, shown below.
-Terpineol is a chiral compound.
Show with an asterisk, (*), the chiral centre(s) in the structure of 
-terpineol.
-Terpineol meets the requirements for E / Z isomerism. However, only one E / Z isomer of 
-terpineol exists.
Explain
• why -terpineol meets the requirements for E / Z isomerism
• whether -terpineol is an E- or Z- isomer
• why only one E / Z isomer of -terpineol exists.
-Terpineol contains two functional groups.
For each functional group, choose a reagent that reacts with that group only. Draw the structures for the organic products of the reactions.
Show structures for organic compounds.
Reagent(s)........
Name of functional group that reacts........
Structure of organic product
Reagent(s)........
Name of functional group that reacts........
Structure of organic product
Cinnamaldehyde and methylcinnamaldehyde are naturally occurring organic compounds.
Methylcinnamaldehyde is an E stereoisomer.
Explain this statement in terms of the Cahn-Ingold-Prelog (CIP) rules.
A student plans to carry out some chemical tests on both cinnamaldehyde and methylcinnamaldehyde.
Suggest a suitable chemical test to confirm that both compounds contain an unsaturated carbon chain.
Your answer should include the reagent and observations.
Describe a chemical test to confirm that both compounds contain an aldehyde functional group.
Your answer should include the reagent and observations.
Describe a chemical test to confirm that cinnamaldehyde and methylcinnamaldehyde contain a carbonyl group.
How could the products of this test be used to distinguish between the two compounds?
Your answer should not include spectroscopy.
A chemist analyses a naturally occurring aromatic compound.
The percentage composition and mass spectrum of the compound are shown below.
Percentage composition by mass: C, 70.58%; H, 5.92%; O, 23.50%.
Mass spectrum
Determine the molecular formula of the compound.
Show your working.
Qualitative tests are carried out on the aromatic compound. The results are shown below.
Determine the functional groups in the compound. Explain your reasoning.
Functional groups........
Explanation........
The carbon-13 NMR spectrum of the compound is shown below.
Using the spectrum and the results from (a) and (b), determine the structure of the compound. Explain your reasoning.
Structure of compound
Memes
Laugh now. Cry in the exam hall later. Then come back and do a past paper.
Mum 💖
how's chemistry going love?? 🥰
we're doing bonding rn
aww that's lovely 💕
📱 Screen time this week · TikTok6h 2m
Chemistry starter pack