14 Alkenes Questions and Answers 2024
(A+)
What is the equation for the direct industrial hydration of alkenes to form alcohols? -
ANS-CH2=CH2 (g) + H2O (g) -> CH3CH2OH (l)
What attacks the double bond in an alkene? - ANS-Electrophiles
What are alkenes? - ANS-unsaturated hydrocarbons
What is the general formula for alkenes? - ANS-CnH2n
Alkenes contain a ______-______ double bond somewhere in their structure -
ANS-double-bond
The arrangement of bonds around the >C=C< is ______ and has the bond angle ___ -
ANS-planer, 120
C=C double covalent bond consists of one _____ (σ) bond and one __(π) bond. -
ANS-sigma, pi
what are the two types of bond in a double carbon bond? - ANS-sigma and pi
Why are double carbon bonds vulnerable to attack by electrophiles? - ANS-π bonds are
exposed and have high electron density.
What are stereoisomers? - ANS-Stereoisomers have the same structural formulae but
have a different spatial arrangement of atoms
What type of stereoisomerism can alkenes exhibit? - ANS-Alkenes can exhibit a type of
isomerism called E-Z stereoisomerism
why do E-Z stereoisomers exist? - ANS-E-Z isomers exist due to restricted rotation
about the C=C bond
Why do E-Z isomers arise? - ANS-(a) There is restricted rotation around the C=C
double bond.
, (b) There are two different groups/atoms attached both ends of the double bond.
How do you name E-Z stereoisomers? - ANS-1. First determine the priority groups on
both sides of the double bond
2. If the priority atom is on the same side of the double bond it is labelled Z from the
german zusammen (The Zame Zide!)
3. If the priority atom is on the opposite side of the double bond it is labelled E from the
german entgegen (The Epposite side!)
The double bonds in alkenes are areas with ____ electron density. This attracts
___________ and the alkenes undergo _______ reactions. - ANS-high, electrons.
additions
What's an electrophile? - ANS-an electron pair acceptor
What's an addition reaction? - ANS-a reaction where two molecules react together to
produce one
With unsymmetrical alkenes a ______ and ______ product can also be formed similar
to the addition of HBr. The same explanation applies. - ANS-minor, major
What is hydrolysis? - ANS-
Reaction of Hydrogen Bromide with Alkenes can lead to two products as the alkene is
____________? - ANS-unsymmetrical
What is Markownikoff's Rule? - ANS-In most cases, bromine will be added to the carbon
with the fewest hydrogens attached to it
In __________ addition to alkenes, the ______ product is formed via the more ______
carbocation intermediate - ANS-electrophillic, major, stable
In electrophilic addition to alkenes why is the major product formed via the more stable
carbocation intermediate? - ANS-This carbocation intermediate is more stable because
-the methyl groups on either side of the positive carbon are electron releasing and
-reduce the charge on the ion which stabilises it.
Direct industrial hydration of alkenes to form alcohols is a - ANS-hydration
What is a hydration reaction? - ANS-a reaction where water is added to a molecule
(A+)
What is the equation for the direct industrial hydration of alkenes to form alcohols? -
ANS-CH2=CH2 (g) + H2O (g) -> CH3CH2OH (l)
What attacks the double bond in an alkene? - ANS-Electrophiles
What are alkenes? - ANS-unsaturated hydrocarbons
What is the general formula for alkenes? - ANS-CnH2n
Alkenes contain a ______-______ double bond somewhere in their structure -
ANS-double-bond
The arrangement of bonds around the >C=C< is ______ and has the bond angle ___ -
ANS-planer, 120
C=C double covalent bond consists of one _____ (σ) bond and one __(π) bond. -
ANS-sigma, pi
what are the two types of bond in a double carbon bond? - ANS-sigma and pi
Why are double carbon bonds vulnerable to attack by electrophiles? - ANS-π bonds are
exposed and have high electron density.
What are stereoisomers? - ANS-Stereoisomers have the same structural formulae but
have a different spatial arrangement of atoms
What type of stereoisomerism can alkenes exhibit? - ANS-Alkenes can exhibit a type of
isomerism called E-Z stereoisomerism
why do E-Z stereoisomers exist? - ANS-E-Z isomers exist due to restricted rotation
about the C=C bond
Why do E-Z isomers arise? - ANS-(a) There is restricted rotation around the C=C
double bond.
, (b) There are two different groups/atoms attached both ends of the double bond.
How do you name E-Z stereoisomers? - ANS-1. First determine the priority groups on
both sides of the double bond
2. If the priority atom is on the same side of the double bond it is labelled Z from the
german zusammen (The Zame Zide!)
3. If the priority atom is on the opposite side of the double bond it is labelled E from the
german entgegen (The Epposite side!)
The double bonds in alkenes are areas with ____ electron density. This attracts
___________ and the alkenes undergo _______ reactions. - ANS-high, electrons.
additions
What's an electrophile? - ANS-an electron pair acceptor
What's an addition reaction? - ANS-a reaction where two molecules react together to
produce one
With unsymmetrical alkenes a ______ and ______ product can also be formed similar
to the addition of HBr. The same explanation applies. - ANS-minor, major
What is hydrolysis? - ANS-
Reaction of Hydrogen Bromide with Alkenes can lead to two products as the alkene is
____________? - ANS-unsymmetrical
What is Markownikoff's Rule? - ANS-In most cases, bromine will be added to the carbon
with the fewest hydrogens attached to it
In __________ addition to alkenes, the ______ product is formed via the more ______
carbocation intermediate - ANS-electrophillic, major, stable
In electrophilic addition to alkenes why is the major product formed via the more stable
carbocation intermediate? - ANS-This carbocation intermediate is more stable because
-the methyl groups on either side of the positive carbon are electron releasing and
-reduce the charge on the ion which stabilises it.
Direct industrial hydration of alkenes to form alcohols is a - ANS-hydration
What is a hydration reaction? - ANS-a reaction where water is added to a molecule
