6C: Alkenes
No description yet. This curated deck is ready for daily study.
Card preview (22)
What is the general formula for alkenes?
Cn H2n
What sort of hydrocarbons are alkenes and cycloalkenes?
Unsaturated hydrocarbons
What is a σ bond?
The overlap of 2 s-orbitals - Stronger than π bonds
What is a π bond?
The overlap of 2 p-orbitals - Weaker than σ bonds
State and explain the relative strength of π bonds and σ bonds.
s-orbitals overlap fully, p-orbitals overlap partially, so σ bonds are stronger.
What is meant by the term electrophile?
A lone pair acceptor.
Reaction of alkenes with hydrogen: Condition, Catalyst, Product, Application.
T = 150 C, Nickel, Alkanes, Manufacture of margarine from vegetable oils.
Describe the reaction Alkene -> Alkane
React with Hydrogen, Nickel Catalyst, T = 150 C.
Reaction of alkenes with halogens: Product, Mechanism.
Dihalogenoalkanes, Electrophilic addition
Describe the reaction Alkene -> Dihalogenoalkane
React with halogen, Electrophilic addition
Reaction of alkenes with hydrogen halides: Product, Mechanism.
Halogenoalkanes, Electrophilic addition
Describe the reaction Alkene -> Halogenoalkane
React with hydrogen halide, Electrophilic addition
Reaction of alkenes with water: Condition, Catalyst, Product.
T > 100 C (Steam), Acid (Dilute phosphoric acid), Alcohols.
Describe the reaction Alkene -> Alcohol
React with steam, Phosphoric acid catalyst.
Reaction of alkenes with Potassium Manganate(VII): Condition, Product, Observation.
Acidic conditions (H2SO4), Diols, Purple -> colourless
Describe the reaction Alkene -> Diol
React with potassium manganate, acidic conditions (H2SO4), Colour change purple -> colourless.
What does heterolytic bond fission of a covalent bond result in?
Formation of ions
What is the relative stability of primary, secondary and tertiary carbocation intermediates?
Primary = least stable Tertiary = most stable
Describe the qualitative test for a C=C double bond, and state the products.
Br(l) -> dihalogenoalkane Br(aq) -> halogen alcohol (major) -> dihalogenoalkane (minor) orange -> colourless
What are three ways of disposing of waste polymers?
• Recycling • Incineration to release energy • Use as a feedstock for cracking
What are two ways chemists limit the problems caused by polymer disposal?
Developing biodegradable polymers, Using chemical scrubbers to remove toxic waste gases caused by incineration of plastics.
Explain how a chemical scrubber can remove toxic waste gases caused by incineration of plastics.
The chemical scrubber is a base which would neutralise the HCl gas.