DF.10

Question 1

Why does product of combustion vary?

Answer 1

Products of combustion vary depending on oxygen availability and undergoes either complete or incomplete combustion.

Question 2

What products are formed in complete combustion?

Answer 2

Carbon dioxide and water.

Question 3

What are some possible products of incomplete combustion?

Answer 3

Carbon monoxide and carbon particulates.

Question 4

What does the formula CxHy represent?

Answer 4

Unburnt hydrocarbon.

Question 5

What polluting effects can particulates have?

Answer 5

Respiratory problems and other health issues.

Question 6

What polluting effects can carbon monoxide have?

Answer 6

It is a toxic gas and can contribute to photochemical smog.

Question 7

What is photochemical smog?

Answer 7

When primary pollutants undergo photochemical reaction by absorbing light energy and resulting in a mixture of primary and secondary pollutants.

Question 8

What are some main green house gases?

Answer 8

• Carbon dioxide
• Methane
• Water vapour
• Nitrous oxide
• Ozone

Question 9

How are oxides of nitrogen made during the combustion of fuels?

Answer 9

Nitrogen and oxygen in the air react when the engine is at a high temperature. Some nitrogen compounds may also be present in fuels but only in very low proportions.

Question 10

How are oxides of sulfur made during the combustion of fuels?

Answer 10

Burning fuels that contain sulfur impurities.

Question 11

What equation shows the production of nitrogen oxide in the car engine?

Answer 11

N2(g) + O2(g) → 2NO(g)

Question 12

What polluting effects can nitrogen oxides have?

Answer 12

They are toxic and can cause acid rain.

Question 13

What polluting effects can sulfur oxides have?

Answer 13

They are toxic and can cause acid rain.

Question 14

Why are there sulfur impurities in fuels?

Answer 14

They are left from past amino acids in fossil fuels.

Question 15

How do nitrogen oxides and sulfur oxides result in acid rain?

Answer 15

When they rise to the upper atmosphere, they react with water to form acids, either weak and strong, depending on the oxide.

Question 16

What effects can acid rain have on the environment and the health?

Answer 16

Acid rain corrodes limestone buildings, kills forests and life in lakes, it also causes respiratory problems in people.

Question 17

Apart from human activity, what is another major source of sulfur oxides?

Answer 17

Volcanic activity.

Question 18

What are pollutants called that were made directly as a result of combustion of fuels?

Answer 18

Primary pollutants.

Question 19

What are pollutants called when they are derived from primary pollutants in the atmosphere?

Answer 19

Secondary pollutants.

Question 20

What effects can photochemical smog have on the environment and health?

Answer 20

Photochemical smog causes haziness and reduced visibility in the air, it also causes respiratory problems in people.

Question 21

What reactions are sped up by catalysts in the engine?

Answer 21

Reactions to convert pollutants to compounds that are naturally present in air, such as carbon dioxide, water and nitrogen.

Question 22

What is the equation for converting carbon monoxide to carbon dioxide?

Answer 22

2CO(g) + O2(g) → 2CO2(g)

Question 23

What is the equation for reacting carbon monoxide and nitrogen oxide to form less polluting products?

Answer 23

2CO(g) + 2NO(g) → 2CO2(g) + N2(g)

Question 24

How does the catalyst help remove unburned hydrocarbons?

Answer 24

Speeding up their complete combustion in oxygen.

Question 25

What is the catalyst known as that speed up the three reactions that removed pollutants from the exhaust?

Answer 25

Three-way catalytic converter.

Question 26

What are these catalytic converter normally consists of?

Answer 26

Platinum or with rhodium.

Question 27

How can sulfur oxide pollutants be best prevented?

Answer 27

By removing sulfur impurities form the fuels before they are made available to motorists.