Chemistry - Chains, Energy and Resources - F322 - Basic Concepts and Hydrocarbons (1) Flashcards
How many known carbon compounds are there?
There are an excess of 10 million known carbon compounds.
What makes a saturated hydrocarbon?
A saturated hydrocarbon contains only single bonds.
What makes an unsaturated hydrocarbon?
An unsaturated hydrocarbon contains at least one carbon-carbon multiple bond
Define an aliphatic hydrocarbon.
An aliphatic hydrocarbon is a hydrocarbon with carbon atoms joined together in straight or branched chains.
Define an alicyclic hydrocarbon
An alicyclic hydrocarbon is a hydrocarbon with carbon atoms joined together in a ring structure.
What is a functional group?
A functional group is the part of a molecule responsible for its chemical reactions.
What is a homologous series?
A homologous series is a series of organic compounds with the same functional group but with each successive member differing by CH2
What are alkanes?
Alkanes are the homologous series with the general formula CnH2n+2.
What is an alkyl group?
An alkyl group is an alkane with a hydrogen atom removed.
Define the empirical formula?
The empirical formula is the simplest whole number ratio of atoms of each element present in a compound.
Define the general formula.
The general formula is the simplest algebraic formula of a member of a homologous series.
What is the displayed formula?
The displayed formula shows the relative positioning of all the atoms in a molecule and the bonds between them.
What is the structural formula?
The structural formula shows the minimal detail for the arrangement of atoms in a molecule.
What is the skeletal formula?
The skeletal formula is a simplified organic formula with the hydrogen atoms removed from alkyl chains leaving just a carbon skeleton and associated functional groups.
What is retinol used for?
Retinol is used to treat acne.
What is salbutamol used for?
Salbutamol is used for the treatment of asthma.
Define a structural isomer.
Structural isomers are molecules with the same molecular formula but with different structural arrangements of atoms.
Give examples of how structural isomerism could occur.
- a hydrocarbon could be branched or unbranched
- a functional group could be in a different position along the main chain
- the functional group could be different (aldehydes vs ketones)
What is a stereoisomer?
A stereoisomer is a compound with the same structural formula, but with a different arrangement of the atoms in space.
Define E/Z isomerism.
E/Z isomerism is a type of stereoisomerism in which different groups attached to each carbon of a C=C double bond may be arranged differently in space because of the restricted rotation of the C=C double bond.
Define cis-trans isomerism.
cis-trans isomerism is a special type of E/Z isomerism in which there is a non-hydrogen group and a hydrogen on each carbon of a C=C double bond: the cis (Z) isomer has the H atoms on each carbon on the same side; the trans (E) isomer has the H atoms on each carbon on different sides.
Define homolytic fission
Homolytic fission is the breaking of a covalent bond with one of the bonded electrons going to each atom, forming two radicals.
What is a radical?
A radical is a species with an unpaired electron.
Define heterolytic fission.
Heterolytic fission is the breaking of a covalent bond with both of the bonded electrons going to one of the atoms, forming a cation (+) and an anion (-).
Define a nucleophile.
A nucleophile is an atom (or group of atoms) that is attracted to an electron-deficient centre or atom, where it donates a pair of electrons to form a new covalent bond.
Define an electrophile
An electrophile is an atom (or group of atoms) that is attracted to an electron-rich centre or atom where it accepts a pair of electrons to form a new covalent bond.
Define fractional distillation.
Fractional distillation is the separation of the components in a liquid mixture into fractions which differ in boiling point (and hence chemical composition) by means of distillation, typically using a fractionating column.
Where do the short-chained hydrocarbons condense in a fractionating column?
Short-chained hydrocarbons condense near the top of a fractionating column.
Where do gases go in a fractionating column?
Gases pass out of an outlet at the top as petroleum gas.
What is the residue at the bottom of the fractionating column?
Bitumen is the residue at the bottom of the fractionating column.
What has lower boiling point, branched or unbranched alkanes and why?
Branched alkanes have lower boiling points because they have fewer points of contact.
What is the main constituent of natural gas?
Methane is the main constituent of natural gas.
What is cracking?
Cracking refers to the breaking down of long-chained saturated hydrocarbons to form a mixture of shorter-chained alkanes and alkenes.
How is most modern cracking performed?
Most modern cracking uses a zeolite catalyst at 450oC.
Unbranched alkanes can sometimes be converted into branched alkanes in a process called….?
Unbranched alkanes can sometimes be converted into branched alkanes in a process called isomerisation.
Aliphatic hydrocarbons can sometimes be converted into cyclic or aromatic hydrocarbons in a process called…?
Aliphatic hydrocarbons can sometimes be converted into cyclic or aromatic hydrocarbons in a process called reforming.
Fuels with a high what rating burn more efficiently?
Fuels with a high octane rating burn more efficiently.
What are petrochemicals?
Petrochemicals are things that can be made from crude oil.
What makes a good fuel?
A good fuel needs to be readily available, easily transported and inexpensive.
What is a biofuel?
A biofuel is a fuel that is derived from recently living material such as plants or from animal waste.
What do alkanes and halogens require in order to react with each other?
Alkanes and halogens will react in the presence of ultraviolet light or temperatures of 300oC
What is radical substitution?
Radical substitution is a type of substitution in which a radical replaces a different atom or group of atoms.
What happens in the initiation step of radical substitution?
Initiation is the first step in a radical substitution in which free radicals are generated by ultraviolet radiation.
What happens in the propagation step of radical substitution?
Propagation is the two repeated steps in radical substitution that build up the products in a chain reaction.
- the number of radicals is always maintained in a propagation step
What happens in the termination step of a radical substitution?
Termination is the step at the end of a radical substitution when two radicals combine to form a molecule.
What is the general formula of aliphatic alkenes?
Aliphatic alkenes have the general formula CnH2n
What forms a pi bond?
A pi bond is formed by the sideways overlap of p orbitals.
What is the bond angle and shape of alkenes?
Alkenes have 120o bond angle and trigonal planar shape.
What is the bond enthalpy of the C=C double bond?
The bond enthalpy of the C=C double bond is +612kJmol-1
What is the bond enthalpy of the C-C single bond?
The bond enthalpy of the C-C single bond is +347kJmol-`
TRUE or FALSE
A pi bond is stronger than a single bond.
FALSE!
A pi bond is weaker than a single bond.
What conditions are required for a hydrogenation reaction?
A hydrogenation reaction occurs in the presence of a nickel catalyst at 150oC
What is used as a test for unsaturation?
The addition of bromine water is used as a test for unsaturation.
When it forms a halogenoalkane it goes colourless, so in the presence of a double bond it’ll go colourless.
The addition of steam to alkenes in the preparation of alcohols requires what conditions?
Steam and alkenes are heated to very high temperatures at very high pressure in the presence of a phosphoric acid catalyst.
What is a carbocation?
A carbocation is an organic ion in which a carbon atom has a positive charge.
What is 1,2-dichloroethane used for?
1,2-dichloroethane is used as a degreaser and paint remover.
What is ethane-1,2-diol used for?
Ethane-1,2-diol is used as antifreeze and one of the key materials for making polyesters such as terylene.
What conditions are required for radical polymerisation?
Radical polymerisation requires temperatures of 200oC and very high pressures.
What conditions does the Ziegler-Natta process require?
The Ziegler-Natta process requires the use of a specialist catalyst such as TiCl3 and Al(C2H5)2Cl at 60oC.
What is the Ziegler-Natta process the common method of production for?
The Ziegler-Natta process is the common method of production for non-branched poly(ethene)
Why is recycling PVC problematic?
Recycling PVC is problematic because of the high chlorine content.
