Fuels and heats

Question 1

what is heat of combustion

Answer 1

heat change when 1 mole of a substance is burned completely in excess oxygen

Question 2

what is heat of reaction

Answer 2

heat change when the number of moles in balanced equation react

Question 3

what is heat of formation

Answer 3

heat change when 1 mole of a compound is formed from its element in their standard states

Question 4

state hess’s law

Answer 4

the heat change for a reaction is the same whether the reaction takes place in one step or in several steps

Question 5

state the law of lavoisier and laplace

Answer 5

heat change for the forward reaction is equal to the heat change for the reverse reaction, but opposite in sign

Question 6

bond energy

Answer 6

is the average energy needed to break one mole of bonds into separate atoms in the gaseous state

Question 7

draw the toxic chemical hazard sign

Answer 7

see diagram in manual

Question 8

draw the flammable hazard symbol

Answer 8

see diagram in the manual

Question 9

draw the environmental hazard symbol

Answer 9

see diagram in manual

Question 10

draw the oxidising agent hazard symbol

Answer 10

see diagram in manual

Question 11

draw the harmful hazard symbol

Answer 11

see diagram in manual

Question 12

draw the irritant hazard symbol

Answer 12

se diagram in manual

Question 13

draw the explosive hazard symbol

Answer 13

see diagram in the manual

Question 14

draw the corrosive hazard symbol

Answer 14

see diagram in the manual

Question 15

what is auto ignition

Answer 15

tendancy to premature ignition

Question 16

what is octane number

Answer 16

tendancy for a fuel to auto ignite

Question 17

aliphatic

Answer 17

consists of chains of carbon atoms

Question 18

hydrocarbon

Answer 18

consist of carbon and hydrogen atoms only

Question 19

homologous series

Answer 19

group of organic compounds that have the same general formula or differ by CH2 or same functional group

Question 20

isomers

Answer 20

same molecular formula but different structural formulas

Question 21

aromatic

Answer 21

has a benzene ring in its structure

Question 22

LPG

Answer 22

liquified petroleum gas

Question 23

methane is a component of natural gas why are mercaptans often added to natural gas

Answer 23

to detect leak

to give an odour

Question 24

what environmental change can or effect is associated with the release of methane to the atmosphere

Answer 24

global warming

greenhouse effect

Question 25

name another source of methane released to the atmosphere

Answer 25

fossil fuels
slurry
dumps

Question 26

draw and name an isomer of butane C4H10

Answer 26

2 methylpropane

see diagram in manual

Question 27

draw and name an isomer of pentane C5H12

Answer 27

2 methylbutane

2,2 dimethylpropane

Question 28

sources of hydrocarbons

Answer 28

coal
petroleum
natural gas

Question 29

why are mercaptans often added to natural gas

Answer 29

to detect leaks

to give an odour

Question 30

what structural feature results in having a high octane rating

Answer 30

short chain

branching

Question 31

give one other structural feature which increases the octane number of a hydrocarbon

Answer 31

aromatic
branching
ring

Question 32

outline clearly how the fractional distillation process is carried

Answer 32

• crude oil is heated at the bottom
• crude added continuously at the bottom
• hot vapour rises up through column
• fractions come off a different levels
• depending on their boiling points
• higher boiling point fractions come off a different levels

Question 33

properties of methane

Answer 33

high heat of combustion
non toxic
relatively cheap

Question 34

why are lead compounds unsuitable as additives for petrol used in modern cars

Answer 34

destroys catalytic converter

catalyst poison