Ch13 Hydrocarbons- alkane

Question 1

5 Fuel properties

Answer 1

1. have high energy output
2. be either abundant or manufactured easily
3. be easy to transport and store
4. be easy to ignite
5. cause minimum environmental damage

Question 2

Saturated compound

Answer 2

a molecules in which all the atoms are linked together by single sigma bonds only

Question 3

hydrocarbon

Answer 3

compound that contains hydrogen and carbon only

Question 4

Trend in boiling point of alkane

Answer 4

Increases as Mr gets larger
- increased chain length and therefore increased electrons present
- more London dispersion forces so more energy required to overcome them

Question 5

Trend in boiling point as branching increases

Answer 5

decreases as degree of branching increases
- less branched can pack together more tightly so have increased surface contact
- creates more London dispersion forces
- more energy is needed to overcome intermolecular forces

Question 6

solubility of alkanes

Answer 6

insoluble in polar solvents
- low polarity so don’t mix with polar molecules

dissolve readily in each other as molecules link through induced dipole-dipole interactions

Question 7

Alkanes chemical properties

Answer 7

unreactive
- CH bonds have low polarity
- single bonds linking CH are relatively strong

Question 8

Combustion of alkanes in excess of oxygen

Answer 8

produces carbon dioxide and water

Question 9

Combustion of alkanes in limited supply of oxygen

Answer 9

produces carbon monoxide/carbon and water

Question 10

Carbon monoxide

Answer 10

poisonous - restricts effectiveness of blood to transport oxygen to body as binds with haemoglobin

Question 11

Carbon

Answer 11

Soot- global dimming

Question 12

Radical

Answer 12

particle that has at least one unpaired electron
highly reactive

Question 13

substitution reaction

Answer 13

an atom(or group) is replaced by another atom

Question 14

Conditions of radical substitution

Answer 14

ultraviolet radiation

Question 15

Steps in radical substitution

Answer 15

1. initiation - starts reaction by forming a radical
2. propagation- maintains reaction by forming one of the products a new radical
3. termination - ends reaction by removing the radicals and forming molecules

Question 16

Homolytic fission

Answer 16

when covalent bond is broken so that the atoms joined by covalent bond each take one of the shared electrons

Question 17

Initiation

Answer 17

UV radiation provides sufficient energy to break covalent bond via homolytic fission, forming 2 radicals

Question 18

Propogation

Answer 18

in first reactions produces hydrogen halide and alkyl radical

in second always produces organic product and regenerates halogen radical