Alkanes as fuels

Question 1

What are the products of the complete combustion of alkanes?

Answer 1

carbon dioxide and water

Question 2

what is the equation for the complete combustion of propane? BALANCE IT!

Answer 2

C3H8 + 5O2 = 3CO2 + 4H2O

Question 3

Wat can the products of incomplete combustion be?

Answer 3

Carbon dioxide, water, carbon monoxide, carbon and unburned hydrocarbons

Question 4

How can you tell carbon is being produced in incomplete combustion?

Answer 4

Smoke or soot being produced.

Question 5

why is carbon monoxide dangerous?

Answer 5

it binds to haemoglobin in red blood cells which stops the body from taking in enough oxygen

Question 6

what is the notation used for unburned hydrocarbons?

Answer 6

HC

Question 7

why is sulfur in crude oil potentially dangerous?

Answer 7

if not removed during distillation, cracking or reforming, sulfur in compounds can be burned and form sulfur dioxide, then react with the atmosphere to form sulfur trioxide.these gases can then dissolve in water to form acids

Question 8

what acid is formed when sulfur trioxide dissolves in water?

Answer 8

sulfuric acid

Question 9

what acid is formed when sulfur dioxide dissolves in water?

Answer 9

sulphurous acid

Question 10

why are oxides of nitrogen quite rare compared to oxides of sulfur?

Answer 10

their combustion occurs at high temperatures, such as the spark plugs in cars

Question 11

how are oxides of nitrogen formed?

Answer 11

nitrogen in alkane fuels react with oxygen molecules in the air under high temperatures

Question 12

what are the three steps from nitrogen to react to form nitrous and nitric acids?

Answer 12

N2 + O2 = 2NO (Nitrogen monoxide formed)
2NO + O2 = 2NO2 (acidic nitrogen dioxide is produced)
2NO2 + H2O = HNO2 + HNO3 (nitrous and nitric acids formed)

Question 13

what precious metals act as catalysts in catalytic converters?

Answer 13

platinum, rhodium and palladium

Question 14

what is the internal structure of catalytic converters?

Answer 14

metal catalyst spread over a honeycomb structure to increase surface area and save money.

Question 15

what gases do three-way catalysts remove?

Answer 15

carbon monoxide, unburned hydrocarbons and oxides of nitrogen

Question 16

what is complete combustion?

Answer 16

means all the atoms in the fuel are fully oxidised

Question 17

what is incomplete combustion

Answer 17

means that only some of the atoms in the fuel are fully oxidised

Question 18

the world has fewer uses for

Answer 18

longer-chained hydrocarbons, so there is a surplus of them

Question 19

the demand for shorter chained hydrocarbons is higher because

Answer 19

they are better fuels and can be used to make other substances such as polymers

Question 20

cracking causes

Answer 20

larger molecules to break into smaller ones

Question 21

octane is used

Answer 21

as one of the hydrocarbons in petrol

Question 22

ethene is used

Answer 22

to make polymers

Question 23

the combustion is engines is

Answer 23

very rapid

Question 24

in engine combustion, not all

Answer 24

hydrocarbons of the right size burn the way

Question 25

hydrocarbons with……chains burn less efficiently than those with………………………………..

Answer 25

straight chains ……..with branched chains or cyclic compounds

Question 26

when pentane is converted in reforming, what is produced?

Answer 26

cyclopentane and hydrogen gas

Question 27

fractional distillation and cracking are different because

Answer 27

fractional distillation involves separating a mixture while cracking involves making new compounds

Question 28

propane is used as

Answer 28

fuel for homes and when camping, sold in high pressure containers

Question 29

the complete combustion of alkanes produces

Answer 29

water and carbon dioxide

Question 30

the products of complete combustion of alkanes are problematic because

Answer 30

carbon dioxide is a greenhouse gas which contributes to the enhanced greenhouse effect, which contributes to climate change

Question 31

combustion of alkanes can also produce other compounds such as

Answer 31

carbon monoxide, carbon, unburned hydrocarbons, oxides of sulfur and oxides of nitrogen

Question 32

the combustion of alkanes can be incomplete because

Answer 32

there is insufficient oxygen present or because combustion is very rapid

Question 33

all of the hydrogen atoms in an alkane molecule is converted to ….. during combustion

Answer 33

water

Question 34

incomplete combustion forms

Answer 34

solid carbon as soot or smoke

Question 35

carbon monoxide is (physical properties)

Answer 35

colourless and odourless

Question 36

catalytic converters used currently are not very efficient at removing

Answer 36

sulfur compounds

Question 37

the best way to remove sulfur pollutants are to

Answer 37

remove sulfur compounds from the fuel before combustion