OCR A-Level Chemistry Synthesis and analytical techniques (02), June 2024: Question 15

1 mark · Medium difficulty · Multiple Choice

Identify the correct statements regarding the disposal and properties of poly(chloroethene) from a given list of three options.

Practise this question

Question

Multiple choice question 15 about the disposal of poly(chloroethene). It shows the chemical structure of poly(chloroethene) with a repeating unit showing carbon atoms bonded to hydrogens and chlorine. Below are three numbered statements about its degradability, incineration products, and recycling as an organic feedstock, followed by four multiple-choice options A, B, C, and D.
Question text

15 Polymers, such as poly(chloroethene), shown below, are difficult to dispose of.

H Cl

C C

H H

Poly(chloroethene)

Which statement(s) is/are true about poly(chloroethene)?

1 It is a photodegradable or biodegradable polymer.

2 When incinerated, it produces toxic waste products which need to be removed.

3 It can be recycled and processed for use as an organic feedstock.

A 1, 2 and 3

B Only 1 and 2

C Only 2 and 3

D Only 1

Your answer

[1]

Mark scheme

Show the mark scheme The mark scheme indicates that an issue affected candidates' ability to answer question 15, so the mark was awarded to all candidates.

15 There was an issue with this question which affected candidates' ability to answer it. To make sure all candidates

were treated fairly, we have awarded the mark to all candidates for this question.

Total 15

SECTION B

How to answer it

Disposal and Properties of Poly(chloroethene)

What this question tests

This question assesses your understanding of polymer chemistry, specifically the environmental impacts and disposal methods associated with addition polymers like poly(chloroethene) (PVC). It covers polymer non-biodegradability, waste products from incineration (such as HCl gas), and the processing of polymers into organic feedstocks.

Question 15 Analysis

Multiple Choice [1 Mark]

✅ Correct Context & Intent

Looking at the statements independently:

  • Statement 1: False. Poly(chloroethene) has a strong carbon-carbon single bond backbone and is saturated, making it non-biodegradable and non-photodegradable under normal environmental conditions.
  • Statement 2: True. Incineration of PVC produces toxic and corrosive hydrogen chloride gas (HCl), which must be scrubbed or removed from waste gases before release.
  • Statement 3: True. Waste polymers can be used as an organic feedstock for the cracking or synthesis of other useful chemical compounds.

This points logically to Only 2 and 3 (Option C).

💡 Key Knowledge

  • Addition Polymers: Polyalkenes like PVC are inert due to strong non-polar C–C and C–H bonds (and polar C–Cl bonds which are still very resistant to direct hydrolysis).
  • Incineration Hazards: Disposal by burning releases hazardous acidic gases like HCl. Acid scrubbers (often using calcium carbonate or alkaline solutions) are mandatory to neutralize this waste.
  • Feedstock Recycling: Polymers can be broken down into monomers or smaller hydrocarbon fragments to serve as raw materials for new plastics and organic chemicals.

🧠 Exam Technique

When tackling "statement" style multiple-choice questions:

  1. Evaluate each statement individually and write T or F next to them on your question paper.
  2. Eliminate options based on your definite truths/falsehoods. For example, knowing statement 1 is false immediately rules out Options A, B, and D, leaving only C.

❌ Common Errors & Examiner Note

Official Exam Board Note: There was an issue with this specific question during live testing/marking which affected candidates' ability to access the intended key. To ensure absolute fairness, the mark was awarded to all candidates.

However, from a revision standpoint, students often incorrectly assume all modern plastics are biodegradable, or forget that chlorine-containing polymers produce toxic acidic gases when burned.

Mark Scheme Allocation: 1 mark total (awarded universally due to exam board question error).

Topics

Module 4: Core organic chemistry · Module 6: Organic chemistry and analysis · 6.2 Nitrogen compounds, polymers and synthesis · 4.1 Basic concepts and hydrocarbons

Question and mark scheme from the OCR A-Level Chemistry examination, Synthesis and analytical techniques (02), June 2024. QuestionVault is an independent revision resource; questions remain the copyright of the awarding body.