Chemistry - 4CH1 PearsonEdexcel

Alkenes

Muhtasari

Alkenes are the reactive cousins of alkanes. A single structural difference - a carbon-carbon double bond - transforms their chemistry completely. Where alkanes are sluggish, alkenes snap up incoming atoms in addition reactions, making them the starting materials for plastics, alcohols, and countless industrial chemicals.

In this lesson you will learn the general formula for alkenes, how to draw and name them, why the double bond makes them unsaturated, and how they react with bromine. You will also discover the bromine water test, a simple way to tell an alkene from an alkane in the laboratory.

Malengo

  1. know that alkenes contain the functional group >C=C<
  2. know the general formula for alkenes
  3. explain why alkenes are classified as unsaturated hydrocarbons
  4. understand how to draw the structural and displayed formulae for alkenes with up to four carbon atoms in the molecule, and name the unbranched-chain isomers knowledge of cis/trans or E/Z notation is not required
  5. describe the reactions of alkenes with bromine to produce dibromoalkanes
  6. describe how bromine water can be used to distinguish between an alkane and an alkene

Maelezo ya Somo

Replace just one single bond between two carbon atoms with a double bond and the entire character of the molecule changes. That double bond is a region of high electron density, making alkenes far more reactive than their alkane counterparts. This reactivity is why the petrochemical industry cracks alkanes to produce alkenes, and why alkenes are the building blocks for polymers like polyethene.

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Tathmini ya Somo

Hongera kwa kukamilisha somo la Alkenes. Sasa kwa kuwa umechunguza dhana na mawazo muhimu, ni wakati wa kuweka ujuzi wako kwa mtihani. Sehemu hii inatoa mazoezi mbalimbali maswali yaliyoundwa ili kuimarisha uelewaji wako na kukusaidia kupima ufahamu wako wa nyenzo.

Utakutana na mchanganyiko wa aina mbalimbali za maswali, ikiwemo maswali ya kuchagua jibu sahihi, maswali ya majibu mafupi, na maswali ya insha. Kila swali limebuniwa kwa umakini ili kupima vipengele tofauti vya maarifa yako na ujuzi wa kufikiri kwa makini.

Tumia sehemu hii ya tathmini kama fursa ya kuimarisha uelewa wako wa mada na kubaini maeneo yoyote ambapo unaweza kuhitaji kusoma zaidi. Usikatishwe tamaa na changamoto zozote utakazokutana nazo; badala yake, zitazame kama fursa za kukua na kuboresha.

  1. What is the general formula for alkenes? A) CnH2n+2 B) CnH2n C) CnH2n-2 D) CnH2n+1OH Answer: B
  2. Which of the following is the functional group of alkenes? A) -OH B) -COOH C) C=C D) C-C Answer: C
  3. When bromine water is added to an alkene, the solution: A) Turns blue B) Stays orange C) Is decolourised D) Turns green Answer: C
  4. The reaction of ethene with bromine is an example of: A) Substitution B) Decomposition C) Neutralisation D) Addition Answer: D
  5. Why is there no alkene with only one carbon atom? A) One carbon cannot form four bonds B) A C=C double bond needs at least two carbon atoms C) Single-carbon molecules are always gases D) Methene is too unstable to exist Answer: B

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Pakua programu ya Green Bridge CBT kwenye simu yako au kompyuta yako ili kupata maelezo kamili ya masomo, maswali ya mazoezi, na mengi zaidi.

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Ungependa kufanya mazoezi ya maswali ya majaribio kuhusu Alkenes? Pakua programu ya Green Bridge CBT ili kupata maswali ya majaribio na tathmini kamili za mazoezi kuhusu mada hii.

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