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IB Chemistry SL 1.1.2 Endothermic Vs Exothermic Questions

Use real exam questions to classify endothermic and exothermic processes, read energy-level diagrams and explain temperature or other observable changes.

Syllabus
First assessment 2025
Course
Chemistry SL
Level
SL

Exam points

  • Classify a process as endothermic or exothermic from temperature change, heat absorbed or released, bond-process evidence or the sign of ΔH.
  • Interpret an enthalpy-level or potential-energy diagram by comparing reactant and product enthalpies and identifying the direction of heat transfer.
  • Explain observable evidence of an exothermic or endothermic process, such as temperature change, melting, sound or other energy transfer to or from the surroundings.

Learn this topic

Study 1.1.2—Endothermic vs. exothermic conceptsOpen the corresponding Concept lesson for explanations, examples and exam connections.

IB Chemistry SL 1.1.2 Endothermic Vs Exothermic Questions question 1

[Maximum number: 1]

Chlorine occurs in Group 7, the halogens.

Chloroethene, H2C=CHCl\mathrm{H}_{2} \mathrm{C}=\mathrm{CHCl}, the monomer used in the polymerization reaction in the manufacture of the polymer poly(chloroethene), PVC, can be synthesized in the following two-stage reaction pathway.

Stage 1: C2H4( g)+Cl2( g)→ClCH2CH2Cl(g)\quad \mathrm{C}_{2} \mathrm{H}_{4}(\mathrm{~g})+\mathrm{Cl}_{2}(\mathrm{~g}) \rightarrow \mathrm{ClCH}_{2} \mathrm{CH}_{2} \mathrm{Cl}(\mathrm{g})

Stage 2: ClCH2CH2Cl(g)→H2C=CHCl(g)+HCl(g)\quad \mathrm{ClCH}_{2} \mathrm{CH}_{2} \mathrm{Cl}(\mathrm{g}) \rightarrow \mathrm{H}_{2} \mathrm{C}=\mathrm{CHCl}(\mathrm{g})+\mathrm{HCl}(\mathrm{g})

State whether the reaction given in stage 1 is exothermic or endothermic.

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