Combustion

Question 1

Chimneys release sulphur dioxide. How do we get rid of sulphur?

Give an equation to represent this

Answer 1

You use a base e.g. Calcium oxide

CaO + SO2 + 1/2 O2 –> CaSO4

Also if under thermal decomposition

CaCO3 + SO2 + 1/2 O2 –> CaSO4 + CO2

Question 2

Give an equation for complete combustion and give the effect of this

Answer 2

CH4 + 2O2 –> CO2 + 2H2O

🌍global warming
🌎greenhouse effect

Question 3

Give an equation for incomplete combustion and give the effect of this

Answer 3

CH4 + 3/2 O2 –> CO + 2H2O

🔥Silent killer
🔥 poisonous

Question 4

Give an equation for very incomplete combustion and give the effect of this

Answer 4

CH4 + O2 –> C + 2H2O

🌑 soot
🌑global dimming

Question 5

Give the equation for flue gas desulfurisation

Answer 5

It’s a neutralization reaction

SO2 + CaO –> CaSO3
Acid + base (alkaline) –> used to make plasterboard

Question 6

Write two equations of oxides of nitrogen can be formed and give the effect of them

Answer 6

N2 + O2 –> NO

N2 + 202 –> 2NO2

🌚smog bad for lungs

N2 and O2 can react because of the heat of engines

Question 7

How does incomplete combustion take place?

Answer 7

If there is a shortage of oxygen

Question 8

What does incomplete combustion produce?

Answer 8

🌖Cabin dioxide
🌖Water
🌖Carbon monoxide
🌖And or soot

Question 9

Does incomplete combustion produce more or less energy than complete combustion?

Answer 9

LESS

Question 10

What is carbon monoxide?

Answer 10

A poisonous gas because it reduces the ability of blood to carry oxygen

Question 11

Give an equation to show incomplete combustion

Answer 11

C8H18 + 8.5 O2 –> 8CO + 9 H2O

Question 12

Give the equation of the combustion of sulphur

Answer 12

S (s) + O2 (g). -> SO2

Question 13

In the combustion of sulphur what does the universal indicator change color to?

Answer 13

Change red to due acid RAIN

Question 14

Sulphur is an impurity in what?

Answer 14

All fossil fuels

Question 15

Give the equations for when sulphur dioxide oxidizes turns to sulphur trioxide

Answer 15

S + O2 –> SO2
SO2 + 1/2 O2 –> SO3
SO3 + H2O –> H2SO4

Question 16

Describe the process of Carbon Neutral

Answer 16

🎋 Plants absorb CO2 as they grow
🌱converted to biodiesel
🌴CO2 produced as biodiesel is burned

🚗 Cars that run on biodiesel produce very little CO2, overall as CO2 is absorbed by the plants used to make the fuel

Question 17

What are free radicals in thermal decomposition?

Answer 17

Free radicals have an unpaired electrons making them reactive

Question 18

What does volatility mean?

Answer 18

Evaporates easily

Easily gives off vapor

Question 19

Describe small molecules in burning hydrocarbons

Answer 19

Small molecules have weak intermolecular forces. Small surface area due to Van del Walls forces

Question 20

What is needed for complete combustion?

Answer 20

Plenty of air is needed to provide enough oxygen for a hydrocarbon fuel to burn completely

Question 21

Give an example of real life combustion

Answer 21

The blue flame of a gas hob or a Bunsen burner

Question 22

What are the products of the complete combustion of a hydrocarbon

Answer 22

Hydrocarbon + oxygen –> carbon dioxide + water

Question 23

Give an equation to represent complete combustion e.g. Pentane

Answer 23

C5H12 + 8O2 –> 5CO2 + 6H2O

Question 24

Describe the burning of hydrocarbons

Answer 24

🏅small molecules (short chain) 
-complete combustion 
-more flammable 
-burns easily 
If this doesn't get enough oxygen then this would be incomplete combustion 

🏅large molecules (long chain)

• incomplete combustion
• harder to burn and a smoky flame
• needs more oxygen for combustion because it’s incomplete