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IB Chemistry HL 3.1.15 Hl Indicator Selection Questions

Use real HL exam questions to choose or reject acid-base indicators by matching their colour-change range to the equivalence region.

Syllabus
First assessment 2025
Course
Chemistry HL
Level
HL

Exam points

  • Select an acid-base indicator whose transition pH range lies within the steep pH change around the titration equivalence point.
  • Use the reacting acid/base strengths, titration curve and indicator transition range to justify whether a proposed indicator is suitable.
  • Reject an indicator when its colour-change range does not overlap the sharp endpoint region, and distinguish the observed endpoint from the equivalence point.

Learn this topic

Study 3.1.15 (HL)—Indicator selection conceptsOpen the corresponding Concept lesson for explanations, examples and exam connections.

IB Chemistry HL 3.1.15 Hl Indicator Selection Questions question 1

[Maximum number: 1]

When nitrogen gas and hydrogen gas are allowed to react in a closed container the following equilibrium is established.

N2( g)+3H2( g)⇌2NH3( g)ΔH=−92.6 kJ\mathrm{N}_{2}(\mathrm{~g})+3 \mathrm{H}_{2}(\mathrm{~g}) \rightleftharpoons 2 \mathrm{NH}_{3}(\mathrm{~g}) \quad \Delta H=-92.6 \mathrm{~kJ}

Identify an indicator from table 16 of the data booklet that could be used for this titration.

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