Alkenes Flashcards

Describe alkenes.

Alkenes are unsaturated hydrocarbons that contain a carbon-carbon double bond somewhere in their structure.

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Describe alkenes.	Alkenes are unsaturated hydrocarbons that contain a carbon-carbon double bond somewhere in their structure.
What is the general formula for alkenes?	The general formula for alkenes is CnH2n.
Define E-Z stereoisomerism.	E-Z stereoisomerism is a type of isomerism exhibited by alkenes, where they have the same structural formula but a different spatial arrangement of atoms.
How are E-Z stereoisomers determined?	E-Z stereoisomers are determined based on the priority groups on both sides of the double bond. The atom with the bigger atomic number is the priority atom.
Describe the difference between Z and E isomers.	Z isomers have the priority atom on the same side of the double bond, while E isomers have the priority atom on the opposite side of the double bond.
Describe electrophilic addition reactions of alkenes.	Electrophilic addition reactions of alkenes involve the addition of an electrophile to the double bond of an alkene, resulting in the formation of a new molecule.
What is the definition of an electrophile?	An electrophile is a molecule or ion that accepts an electron pair during a chemical reaction.
How does the electron density in alkenes attract electrophiles?	The double bonds in alkenes have high electron density, which attracts electrophiles.
Define addition reaction.	An addition reaction is a chemical reaction where two molecules react together to produce one new molecule.
Describe the reaction of bromine with alkenes.	When bromine reacts with alkenes, a dihalogenoalkane is formed through an electrophilic addition mechanism.
Describe the reaction of sulfuric acid with alkenes.	The reaction involves two stages: electrophilic addition and hydrolysis. In the first stage, the alkene reacts with concentrated sulfuric acid to form an alkyl hydrogensulfate. In the second stage, the alkyl hydrogensulfate reacts with water to form an alcohol and regenerate sulfuric acid as a catalyst.
What is the role of sulfuric acid in the reaction with alkenes?	Sulfuric acid acts as a catalyst in the reaction. It is regenerated in the second stage of the reaction and helps facilitate the conversion of alkenes to alcohols.
Define hydrolysis.	Hydrolysis is a reaction where a molecule is split by the addition of water. In the context of the reaction between sulfuric acid and alkenes, hydrolysis refers to the second stage where the alkyl hydrogensulfate is converted to an alcohol.
How can alkenes be converted to alcohols industrially?	In the industrial process of hydration, alkenes are reacted with water in the presence of an acid catalyst. This one-step reaction allows for the direct conversion of alkenes to alcohols, unlike the two-stage reaction with sulfuric acid.
What is the purpose of testing for alkenes with bromine water?	Bromine water can be used as a test for the presence of a double bond in a molecule. It decolorizes in the presence of a double bond, allowing for the qualitative detection of alkenes. It can also be used quantitatively to determine the presence of multiple double bonds in compounds like polyunsaturated oils.
What are addition polymers formed from?	Alkenes
Describe addition polymerisation.	It is the process of forming addition polymers from alkenes.
What is the repeating unit in poly(alkene)?	The repeating unit is the monomer.
What are some properties of poly(chloroethene)?	It is waterproof, an electrical insulator, and does not react with acids.
How does the addition of a plasticiser affect the flexibility of PVC?	It weakens the intermolecular forces, allowing the chains to move more easily and increasing flexibility.
Define un-plasticised PVC.	It is a rigid form of PVC due to strong intermolecular bonding between polymer chains.
What is the purpose of adding plasticisers to PVC?	To increase flexibility and make it suitable for applications such as insulation and waterproof clothing.
Describe the structure of poly(propene).	Poly(propene) has repeating units with a propene monomer and groups of atoms arranged around the double bond.

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