Chemistry - Chains, Energy and Resources - F322 - Basic Concepts and Hydrocarbons (1)

Question 1

How many known carbon compounds are there?

Answer 1

There are an excess of 10 million known carbon compounds.

Question 2

What makes a saturated hydrocarbon?

Answer 2

A saturated hydrocarbon contains only single bonds.

Question 3

What makes an unsaturated hydrocarbon?

Answer 3

An unsaturated hydrocarbon contains at least one carbon-carbon multiple bond

Question 4

Define an aliphatic hydrocarbon.

Answer 4

An aliphatic hydrocarbon is a hydrocarbon with carbon atoms joined together in straight or branched chains.

Question 5

Define an alicyclic hydrocarbon

Answer 5

An alicyclic hydrocarbon is a hydrocarbon with carbon atoms joined together in a ring structure.

Question 6

What is a functional group?

Answer 6

A functional group is the part of a molecule responsible for its chemical reactions.

Question 7

What is a homologous series?

Answer 7

A homologous series is a series of organic compounds with the same functional group but with each successive member differing by CH2

Question 8

What are alkanes?

Answer 8

Alkanes are the homologous series with the general formula CnH2n+2.

Question 9

What is an alkyl group?

Answer 9

An alkyl group is an alkane with a hydrogen atom removed.

Question 10

Define the empirical formula?

Answer 10

The empirical formula is the simplest whole number ratio of atoms of each element present in a compound.

Question 11

Define the general formula.

Answer 11

The general formula is the simplest algebraic formula of a member of a homologous series.

Question 12

What is the displayed formula?

Answer 12

The displayed formula shows the relative positioning of all the atoms in a molecule and the bonds between them.

Question 13

What is the structural formula?

Answer 13

The structural formula shows the minimal detail for the arrangement of atoms in a molecule.

Question 14

What is the skeletal formula?

Answer 14

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.

Question 15

What is retinol used for?

Answer 15

Retinol is used to treat acne.

Question 16

What is salbutamol used for?

Answer 16

Salbutamol is used for the treatment of asthma.

Question 17

Define a structural isomer.

Answer 17

Structural isomers are molecules with the same molecular formula but with different structural arrangements of atoms.

Question 18

Give examples of how structural isomerism could occur.

Answer 18

• 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)

Question 19

What is a stereoisomer?

Answer 19

A stereoisomer is a compound with the same structural formula, but with a different arrangement of the atoms in space.

Question 20

Define E/Z isomerism.

Answer 20

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.

Question 21

Define cis-trans isomerism.

Answer 21

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.

Question 22

Define homolytic fission

Answer 22

Homolytic fission is the breaking of a covalent bond with one of the bonded electrons going to each atom, forming two radicals.

Question 23

What is a radical?

Answer 23

A radical is a species with an unpaired electron.

Question 24

Define heterolytic fission.

Answer 24

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 (-).

Question 25

Define a nucleophile.

Answer 25

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.

Question 26

Define an electrophile

Answer 26

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.

Question 27

Define fractional distillation.

Answer 27

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.

Question 28

Where do the short-chained hydrocarbons condense in a fractionating column?

Answer 28

Short-chained hydrocarbons condense near the top of a fractionating column.

Question 29

Where do gases go in a fractionating column?

Answer 29

Gases pass out of an outlet at the top as petroleum gas.

Question 30

What is the residue at the bottom of the fractionating column?

Answer 30

Bitumen is the residue at the bottom of the fractionating column.

Question 31

What has lower boiling point, branched or unbranched alkanes and why?

Answer 31

Branched alkanes have lower boiling points because they have fewer points of contact.

Question 32

What is the main constituent of natural gas?

Answer 32

Methane is the main constituent of natural gas.

Question 33

What is cracking?

Answer 33

Cracking refers to the breaking down of long-chained saturated hydrocarbons to form a mixture of shorter-chained alkanes and alkenes.

Question 34

How is most modern cracking performed?

Answer 34

Most modern cracking uses a zeolite catalyst at 450oC.

Question 35

Unbranched alkanes can sometimes be converted into branched alkanes in a process called....?

Answer 35

Unbranched alkanes can sometimes be converted into branched alkanes in a process called isomerisation.

Question 36

Aliphatic hydrocarbons can sometimes be converted into cyclic or aromatic hydrocarbons in a process called...?

Answer 36

Aliphatic hydrocarbons can sometimes be converted into cyclic or aromatic hydrocarbons in a process called reforming.

Question 37

Fuels with a high *what* rating burn more efficiently?

Answer 37

Fuels with a high octane rating burn more efficiently.

Question 38

What are petrochemicals?

Answer 38

Petrochemicals are things that can be made from crude oil.

Question 39

What makes a good fuel?

Answer 39

A good fuel needs to be readily available, easily transported and inexpensive.

Question 40

What is a biofuel?

Answer 40

A biofuel is a fuel that is derived from recently living material such as plants or from animal waste.

Question 41

What do alkanes and halogens require in order to react with each other?

Answer 41

Alkanes and halogens will react in the presence of ultraviolet light or temperatures of 300oC

Question 42

What is radical substitution?

Answer 42

Radical substitution is a type of substitution in which a radical replaces a different atom or group of atoms.

Question 43

What happens in the initiation step of radical substitution?

Answer 43

Initiation is the first step in a radical substitution in which free radicals are generated by ultraviolet radiation.

Question 44

What happens in the propagation step of radical substitution?

Answer 44

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

Question 45

What happens in the termination step of a radical substitution?

Answer 45

Termination is the step at the end of a radical substitution when two radicals combine to form a molecule.

Question 46

What is the general formula of aliphatic alkenes?

Answer 46

Aliphatic alkenes have the general formula CnH2n

Question 47

What forms a pi bond?

Answer 47

A pi bond is formed by the sideways overlap of p orbitals.

Question 48

What is the bond angle and shape of alkenes?

Answer 48

Alkenes have 120o bond angle and trigonal planar shape.

Question 49

What is the bond enthalpy of the C=C double bond?

Answer 49

The bond enthalpy of the C=C double bond is +612kJmol-1

Question 50

What is the bond enthalpy of the C-C single bond?

Answer 50

The bond enthalpy of the C-C single bond is +347kJmol-`

Question 51

TRUE or FALSE | A pi bond is stronger than a single bond.

Answer 51

FALSE! | A pi bond is weaker than a single bond.

Question 52

What conditions are required for a hydrogenation reaction?

Answer 52

A hydrogenation reaction occurs in the presence of a nickel catalyst at 150oC

Question 53

What is used as a test for unsaturation?

Answer 53

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.

Question 54

The addition of steam to alkenes in the preparation of alcohols requires what conditions?

Answer 54

Steam and alkenes are heated to very high temperatures at very high pressure in the presence of a phosphoric acid catalyst.

Question 55

What is a carbocation?

Answer 55

A carbocation is an organic ion in which a carbon atom has a positive charge.

Question 56

What is 1,2-dichloroethane used for?

Answer 56

1,2-dichloroethane is used as a degreaser and paint remover.

Question 57

What is ethane-1,2-diol used for?

Answer 57

Ethane-1,2-diol is used as antifreeze and one of the key materials for making polyesters such as terylene.

Question 58

What conditions are required for radical polymerisation?

Answer 58

Radical polymerisation requires temperatures of 200oC and very high pressures.

Question 59

What conditions does the Ziegler-Natta process require?

Answer 59

The Ziegler-Natta process requires the use of a specialist catalyst such as TiCl3 and Al(C2H5)2Cl at 60oC.

Question 60

What is the Ziegler-Natta process the common method of production for?

Answer 60

The Ziegler-Natta process is the common method of production for non-branched poly(ethene)

Question 61

Why is recycling PVC problematic?

Answer 61

Recycling PVC is problematic because of the high chlorine content.