3.2.3 Combustion of Alkanes

Question 1

What does incomplete combustion produce in hydrocarbons

Answer 1

CO + H2O

Question 2

What does complete combustion produce in hydrocarbons

Answer 2

CO2 + H2O

Question 3

Where might incomplete combustion occur?

Answer 3

Inside a car engine because there is limited O2 present. Carbon is formed as soot.

Question 4

What do exhaust fumes contain?

Answer 4

• CO
• NO and NO2
• Volatile organic compounds
• Unburned hydrocarbons
• Damage environment

Question 5

Effects of CO

Answer 5

• Toxic and odourless
• Can cause dizziness, loss of consciousness and death
• CO binds to haemoglobin and so cannot bind to O2 and so O2 is not transported to organs

Question 6

Effects of nitrous oxides

Answer 6

• In car engine, temps are hot enough to force nitrogen to be oxidised

N2(g) + O2(g) → 2NO(g)

N2(g) + 2O2(g) → 2NO2(g)

Nitrous oxides can react with volatile organic compounds in the air to create PAN, contributing to smog in atmosphere and can be harmful to lungs eyes and plants

Can also dissolve in water and react with oxygen forming nitric acid causing acid rain. Can dissolve construction and cause harm to aquatic life

Question 7

What is catalytic removal

Answer 7

Catalytic converters remove pollutants

Platinum coated in honeycomb to provide large SA

Put in exhaust pipes.