Seneca 7.2 Flashcards
What is the formula for alkenes
A homologous series is a series of compounds with the same general formula.
Alkenes are a homologous series with the general formula CnH2n.
What are the properties of alkenes
. Unsaturated
. More reactive than alkenes
. Contain a double bond
Why are alkenes unsaturated
they contain a double bond between two of their carbon atoms (C=C).
This means that an alkane and alkene with the same length of carbon chain will have different numbers of hydrogen atoms - the alkane will have two more hydrogen atoms.
What are alkenes
Alkenes are hydrocarbons with the functional group C=C. This means that alkenes have a carbon-carbon double
bond.
Why are alkenes more reactive than alkanes
The presence of the C=C functional group means that alkenes have greater reactivity than alkanes.
What are the four shortest alkenes in ascending order
.Ethene C2H4
.Propene C3H6
.Butene C4H8
.Pentene C5H10
Addition reaction
When a double bond opens up allowing new atoms to bond.
Functional group
A collection of atoms that impact the reactions of an organic compound.
Alkenes and oxygen
Alkenes can be involved in combustion reactions with oxygen. The outcome of these reactions is similar to when other hydrocarbons react with oxygen
Ethene (C2H4) + oxygen (O2) → carbon monoxide (CO) + carbon (C) + water (H2O)
Because their combustion is incomplete, they burn with smoky flames.
Alkenes and halogens
Alkenes, unlike alkanes, will react if mixed with bromine water and shaken. This causes the solution to change color from orange-brown to colorless.
This is an effective test for distinguishing between alkenes and alkanes
Alkenes and hydrogen
When a nickel catalyst is present, alkanes can be formed by combining hydrogen with an alkene
Adding hydrogen atoms across a carbon-carbon double bond is called hydrogenation.
Ethene (C2H4) + hydrogen (H2) → ethane (C2H6)
Alkenes and water
When a phosphoric acid catalyst is present, alcohols can be formed by reacting alkenes with steam
Ethene (C2H4) + steam (H2O) → ethanol (C2H5OH)
What happens during an alkene addition reaction
A carbon - carbon double bond opens up
What is the functional group of alkenes
C=C
What do you need for alkenes to react with water
. The water to be in a gaseous state
. A phosphoric acid catalyst
What is the general series (homologous series) of alcohols
The homologous series of alcohols have the general formula
CnH2n+1 OH.
What is the functional group of alcohols
The functional group of alcohols is a hydroxyl group (-OH).
What are the 4 smallest alcohols in ascending size order
.Methanol CH3OH
.Ethanol CH3CH2OH
.Propanol CH3CH2CH2OH
.Butanol CH3CH2CH2CH2OH
What are the properties of alcohol
. Hydroxyl group
. General formula is CnH2n+1 OH.
What happens when alcohols and sodium react together
When alcohols and sodium react together, hydrogen is produced.