Alkenes Flashcards
Alkenes are considered ________ hydrocarbons due to the presence of ________
Unsaturated, Carbon-Carbon Double Bonds
What are the names and chemical formulas of the first three members of the alkene homologous series
Ethene C₂H₄ or CH₂=CH₂
Propene C₃H₆ or CH₂=CH₂CH₃
Butene: C₄H₈
(But-1-ene: CH₂=CH₂CH₂CH₃
But-2-ene: CH₃CH₂=CH₂CH₃)
What are the three TYPES of reactions that alkenes can undergo?
Combustion, Addition, and Addition Polymerisation
What are the products of the combustion of any alkene?
Carbon Dioxide and Water
What are the three possible addition reactions that are possible with alkenes?
- Hydrogenation
- Bromination
- Hydration
What are the reagents and conditions, and product for the addition of hydrogen (hydrogenation)?
- Ni Catalyst
- 200 Degrees Celsius
- Hydrogen Gas
Product: Alkane (Saturated)
What are the reagents, conditions, and observations for the addition of Bromine (bromination)?
- rtp
- aqueous or liquid Bromine
Brown solution turns colourless
What are the reagents, conditions, and products for the addition of water (hydration)?
- Phosporic (V) Acid
- 60-70atm
- 300 Degrees Celsius
Product: Alcohol
What are the conditions required for addition polymerisation?
- High Temperature and Pressure
2. Suitable Catalyst
What is/are the method(s) for producing alkenes?
one of the methods is an extension of the syllabus
- Cracking of long chain Hydrocarbons
2. Dehydration of Alcohol (Elimination of water)
What are the reagents, conditions, and products for Cracking?
- 600 Degrees Celsius
- Silicon (IV) Oxide or Aluminium Oxide
Products: Mixture of shorter chain alkanes, alkenes and hydrogen gas.
What are the reagents and conditions for the elimination of water from alcohols to produce alkenes?
Concentrated Sulfuric Acid
Heat under reflux
How does one test for the presence of alkenes?
Add a few drops of Aqueous or Liquid Bromine. The brown Bromine will turn colourless if alkene is present.
How is margerine produced? Give the reagents and conditions.
Hydrogenation of unsaturated vegetable oils. 200 degrees celcius, Ni Catalyst
What is the general formula for alkenes?
CₙH₂ₙ
