4B.2 Alkanes as fuels

Question 1

what is combustion

Answer 1

it is a chemical reaction in which a compound reacts with oxygen

Question 2

what are the products of combustion

Answer 2

1. H2O

2. CO2

Question 3

which product of combustion is bad and why

Answer 3

CO2 because it is a greenhouse gas that contributes to global warming and climate change

Question 4

how does carbon dioxide work

Answer 4

it works by trapping the infrared radiation emitted from the earth surface stopping it from escaping the earth

Question 5

what is complete combustion

Answer 5

it is a reaction in which all the atoms in fuel are fully oxidized, producing only carbon dioxide and water

Question 6

what is incomplete combustion

Answer 6

reaction in which some of the atoms in the fuel are not fully oxidized producing carbon dioxide, carbon monoxide, and soot (unburnt carbon)

Question 7

why may incomplete combustion reactions occur

Answer 7

because there isn’t enough oxygen present, or because the combustion is very rapid

Question 8

what is an example of soot forming

Answer 8

C3H8 + 4O2 ——> C + 2CO + 4H2O

Question 9

how toxic is soot

Answer 9

it can be harmful but not fatal

Question 10

example of the formation of CO

Answer 10

C3H8 + 4O2 ——> 2CO + CO2 + 4H2O

Question 11

How toxic is carbon monoxide

Answer 11

it is fatal

Question 12

what is carbon monoxide

Answer 12

it is a colourless odourless toxic gas that causes the death of people each year. it acts by preventing the transport of oxygen around the body

Question 13

what are unburned hydrocarbons

Answer 13

they are products of incomplete combustion where the hydrocarbon itself isn’t burned at all, resulting in a tiny portion of unchanged hydrocarbon being released into the atmosphere

Question 14

what are oxides of sulfur

Answer 14

some molecules in crude oil might have sulfur impurities that can’t be removed by reforming, cracking, and fractional distillation. when the crud email undergoes combustion some of the sulfur might react with the oxygen forming SO2 and 2SO3 which are both acidic oxides so when released into the atmosphere they can dissolve in water to form sulfurous acid H2SO3 and sulfuric acid H2SO4 which both contribute to acidic rain that can damage the aquatic life and the growing of crops

Question 15

what is the equation for the oxidation of sulfur

Answer 15

S + O2 ——> SO2

Question 16

what is the equation for the oxidation of sulfur oxide

Answer 16

2SO2 + O2 —–> 2SO3

Question 17

What is the equation for SO2 dissolving in water

Answer 17

SO2 + H2O —–> H2SO3

Question 18

What is the equation for SO3 dissolving in water?

Answer 18

SO3 + H2O —–> H2SO4

Question 19

oxides of nitrogen

Answer 19

very small molecules of alkanes can include nitrogen atoms (even thoughit is very unlikely to use alkanes that include nitrogen as a fuel). so in composition under very high temperatures (especially in car spark plugs) the nitrogen from the air can react with oxygen causing nitrogen oxide. which are represented with the formula of NOx Now we can have a lot of nitrogen oxides but the ones formed in the reaction are nitrogen monoxide and nitrogen dioxide. Carbon dioxide is an acidic oxide so when it is dissolved in water it can form nitrous and nitric acid affecting the equate life and damaging the crops and forests

Question 20

what is the equation of oxidation of Nitrogen

Answer 20

N2 + O2 —–> 2NO

Question 21

what is the equation of oxidation of Nitrogen monooxide

Answer 21

2NO + O2 —–> 2NO2

Question 22

What is the equation for 2NO2 dissolving in water

Answer 22

2NO2 + H2O ——–> HNO2 + HNO3

Question 23

What are catalytic converters

Answer 23

they are devices that are fitted near the exhaust system that convert toxic materials of incomplete combustion to normal materials they are made up of precious metals such as, platinum, rhodium, and palladium, which are spread over a tiny honeycomb mush to increase the surface area and to save money

Question 24

what is the three-way catalyst

Answer 24

a type of catalytic converter that can remove carbon monoxide, unburnt hydrocarbons, and oxides of nitrogens

Question 25

what are the three reactions that occur in the three-way catalyst

Answer 25

1. oxidation of unburned hydrocarbons:
C8H18 + 12.5O ------> 8CO2 + 9H2O
2. oxidation of carbon monoxide:
2CO2 + O2 ------> 2CO2 
3. 2NO + 2CO -----> N2 + 2CO2

Question 26

what is the best way to deal with sulfur oxides

Answer 26

by removing sulfur before using the fuel