Organic Chemistry II | Edexcel A-Level Chemistry (9CH0)
Organic Chemistry II
- 113 questions
- 8 subtopics
- Paper 2: advanced organic and physical chemistry
- Paper 2 and Paper 3
Covers chirality, the aldehydes and ketones with the tests that tell them apart, their reduction and addition reactions, the carboxylic acids, esters and acyl chlorides, and the practical techniques for making and purifying an organic product..
It covers chirality, aldehydes, ketones and their oxidation, reduction and nucleophilic addition of HCN, testing for a carbonyl group: 2,4-DNPH and the iodoform reaction, carboxylic acids and their reactions, esters and acyl chlorides, reflux, extraction and recrystallisation and distillation, melting temperature and working safely.
Sample questions from Organic Chemistry II
Answer each one closed book first, then open the answer.
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Chirality
In an Sₙ1 reaction of a chiral halogenoalkane, what happens in the first step?
Show the answer
The chiral halogenoalkane loses the halide ion to form a carbocation -
Aldehydes, ketones and their oxidation
Why is the carbonyl carbon open to attack by a nucleophile?
Show the answer
Oxygen is considerably more electronegative than carbon, so the C=O bond is strongly polarised and the carbon carries a partial positive charge that attracts an electron-rich species. -
Reduction and nucleophilic addition of HCN
How is the reducing agent written in equations for these reactions?
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As [H], so the reduction of propanone is written CH₃COCH₃ + 2[H] → CH₃CH(OH)CH₃. -
Testing for a carbonyl group: 2,4-DNPH and the iodoform reaction
How is 2,4-DNPH used to identify which carbonyl compound is present?
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The derivative is filtered, purified by recrystallisation and its melting temperature measured. Comparing that value with tabulated melting temperatures of known derivatives identifies the original compound. -
Carboxylic acids and their reactions
Give two ways a carboxylic acid can be prepared.
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By oxidising a primary alcohol or an aldehyde with acidified dichromate(VI) under reflux, or by hydrolysing a nitrile with dilute acid under reflux. -
Esters and acyl chlorides
What is formed when an ester is hydrolysed by heating with sodium hydroxide?
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The sodium salt of the carboxylic acid and the alcohol. Because the salt does not react back, this hydrolysis goes to completion. -
Reflux, extraction and recrystallisation
Which layer is discarded during purification by washing?
Show the answer
The layer containing the impurities is discarded. -
Distillation, melting temperature and working safely
What happens during co-distillation in steam distillation?
Show the answer
The organic compound and water distil together at a temperature below 100°C.
The 8 subtopics
One subtopic is one session. Work down the list.
| Subtopic | What it covers | Questions |
|---|---|---|
| Chirality | Chiral centres and optical isomers, how they rotate plane-polarised light, racemic mixtures, and using the optical activity of the product to tell an Sₙ1 mechanism through a planar carbocation from an Sₙ2 mechanism with inversion. | 19 |
| Aldehydes, ketones and their oxidation | Recall questions on naming and structure, on physical properties, and on the Tollens', Fehling's and dichromate tests that distinguish an aldehyde from a ketone. | 15 |
| Reduction and nucleophilic addition of HCN | Reducing aldehydes to primary alcohols and ketones to secondary alcohols with lithium tetrahydridoaluminate, LiAlH₄, in dry ether, writing the reducing agent as [H], the nucleophilic addition of HCN with KCN to give a hydroxynitrile, and why the product is a racemic mixture. | 8 |
| Testing for a carbonyl group: 2,4-DNPH and the iodoform reaction | Recall questions on the 2,4-DNPH test and its orange precipitate, on identifying a carbonyl from its melting temperature, and on what a positive iodoform test proves. | 8 |
| Carboxylic acids and their reactions | The carboxyl group, hydrogen-bonded dimers and solubility, why carboxylic acids are weak, preparing them by oxidation or nitrile hydrolysis, and their reactions with metals, sodium carbonate, sodium hydroxide, LiAlH₄, phosphorus(V) chloride and alcohols. | 13 |
| Esters and acyl chlorides | Recall questions on esterification and its catalyst, on acid and alkaline hydrolysis, on the uses of esters, and on the reactions of acyl chlorides. | 15 |
| Reflux, extraction and recrystallisation | Recall questions on why a reaction is refluxed, on solvent extraction in a separating funnel, and on the steps of a recrystallisation. | 18 |
| Distillation, melting temperature and working safely | Simple and steam distillation, judging purity from a sharp or broad melting range, using hazard data to select and justify control measures, the techniques in the aspirin preparation of Core Practical 16, and why Grignard reactions need dry ether. | 17 |
How the guide is worked
Answering a question from memory stores it far better than reading the answer again. The guide runs that as a fixed procedure on one subtopic at a time, about twenty minutes a session.
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Step 1 · Closed book
Cover the answers. Work through one subtopic and write down what you can. Leave blanks where you have nothing.
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Step 2 · Open book
Go back to the top. Read each printed answer and write it out in full, including the ones you had right.
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Step 3 · Closed book again
Same questions, same order, from memory. The gap between pass one and pass three is the session result.
Read the full method, the return schedule and the research behind it.
Nearby topics
Edexcel A-Level Chemistry Active Recall Guide
Every topic, not just this one. 1,534 questions with their answers.