ChemistryChapter 16: Hydrocarbons
Alkynes (school) — Reactions
H2 excess -> alkane (named stages alkene then alkane if limited H2).
Learning objectives
- Define reactions using accurate chemistry terms.
- Explain why reactions matters within alkynes (school).
- Apply the learning unit to an FBISE-style example, comparison, diagram, or calculation.
Definition
H2 excess -> alkane (named stages alkene then alkane if limited H2). Br2 decolourise, more Br2 needed. Water addition named if the book has carbonyl from ethyne (school name only). Test: ethyne burns smoky flame; ammoniacal CuCl precipitate with terminal alkyne. This page separates the idea from the wider topic “ALKYNES (SCHOOL)” so it can be revised and assessed on its own.
Important terms
- REACTIONS
- H2 excess -> alkane (named stages alkene then alkane if limited H2).
- ALKYNES (SCHOOL)
- Alkynes: C triple C, CnH2n-2 (one triple).
Overview
Study this learning unit in three steps:
Key Idea
H2 excess -> alkane (named stages alkene then alkane if limited H2). Br2 decolourise, more Br2 needed. Water addition named if the book has carbonyl from ethyne (school name only). Test: ethyne burns smoky flame; ammoniacal CuCl precipitate with terminal alkyne.
Examples More Br2 · Hydrogenate named · No welding-gas misuse
Exam Application
Exam alkyne vs alkene: alkyne has a triple bond, more unsaturation can add more Br2 than an alkene both decolourise Br2; alkanes do not
Examples More Br2 · Hydrogenate named · No welding-gas misuse
WHAT — ALKYNES (SCHOOL) — REACTIONS
H2 excess -> alkane (named stages alkene then alkane if limited H2). Br2 decolourise, more Br2 needed. Water addition named if the book has carbonyl from ethyne (school name only). Test: ethyne burns smoky flame; ammoniacal CuCl precipitate with terminal alkyne. This page separates the idea from the wider topic “ALKYNES (SCHOOL)” so it can be revised and assessed on its own.
WHY — Why this topic matters
ALKYNES (SCHOOL) — REACTIONS is an independent FBISE learning unit because students must use its definitions, conditions, equations, or trends separately in explanations and calculations.
HOW — How it works
H2 excess -> alkane (named stages alkene then alkane if limited H2). Br2 decolourise, more Br2 needed. Water addition named if the book has carbonyl from ethyne (school name only). Test: ethyne burns smoky flame; ammoniacal CuCl precipitate with terminal alkyne. Examples: More Br2; Hydrogenate named; No welding-gas misuse. Exam use: Exam alkyne vs alkene: alkyne has a triple bond, more unsaturation can add more Br2 than an alkene both decolourise Br2; alkanes do not
Explanation
H2 excess -> alkane (named stages alkene then alkane if limited H2). Br2 decolourise, more Br2 needed. Water addition named if the book has carbonyl from ethyne (school name only). Test: ethyne burns smoky flame; ammoniacal CuCl precipitate with terminal alkyne. Examples: More Br2; Hydrogenate named; No welding-gas misuse. Exam use: Exam alkyne vs alkene: alkyne has a triple bond, more unsaturation can add more Br2 than an alkene both decolourise Br2; alkanes do not
In simple words
Federal Board Class 11 Chemistry learning unit. Easy wording; no provincial-board material added.
Key points
- two pi bonds
- more Br2
Exam preparation
Exam Focus
Quick revision
Revision Zone
Review the key facts, formulas and checks before you move on.Alkynes (school) — Reactions
Sticky Notes · Quick Revision
Core idea
- H2 excess -> alkane (named stages alkene then alkane if limited H2). Br2 decolourise, more Br2 needed. Water addition named if the book has carbonyl from ethyne (school name only). Test: ethyne burns smoky flame; ammoniacal CuCl precipitate with terminal alkyne. This page separates the idea from the wider topic “ALKYNES (SCHOOL)” so it can be revised and assessed on its own.
WHAT
- H2 excess -> alkane (named stages alkene then alkane if limited H2).
WHY
- ALKYNES (SCHOOL) — REACTIONS is an independent FBISE learning unit because students must use its definitions, conditions, equations, or trends separately in explanations and calculations.
HOW
- H2 excess -> alkane (named stages alkene then alkane if limited H2). Br2 decolourise, more Br2 needed. Water addition named if the book has carbonyl from ethyne (school name only). Test: ethyne burns smoky flame; ammoniacal CuCl precipitate with terminal alkyne. Examples: More Br2; Hydrogenate named; No welding-gas misuse. Exam use: Exam alkyne vs alkene: alkyne has a triple bond, more unsaturation can add more Br2 than an alkene both decolourise Br2; alkanes do not
Common misconception
- Do not treat reactions as the same as every other part of alkynes (school); define this unit and use its own evidence, steps, or conditions.
FBISE exam check
- Define alkynes (school) — reactions, explain how it works, and support the answer with one relevant example.
60-second revision
- H2 excess -> alkane (named stages alkene then alkane if limited H2).
- More Br2
- Exam link: two pi bonds.
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