Combustion (8E)

Question 2

1) What is a greenhouse gas?
2) How is the greenhouse effect caused?
3) How does the greenhouse effect cause global warming?

Answer 2

1) Greenhouse gases are gases in the earth’s atmosphere that trap heat. During the day, the sun shines through the atmosphere, warming the earth’s surface. At night the earth’s surface cools, releasing heat back into the air. But some of the heat is trapped by the greenhouse gases in the atmosphere.
2) Burning fossil fuels like coal and oil puts more carbon dioxide into our atmosphere, too much of these greenhouse gases can cause Earth’s atmosphere to trap more and more heat. This causes Earth to warm up.
3) Some gases in the Earth’s atmosphere act a bit like the glass in a greenhouse, trapping the sun’s heat and stopping it from leaking back into space and causing global warming

Question 3

1) Where are the 5 places radiation can travel?

Answer 3

1) 1. Some solar radiation is reflected by the earth and the atmosphere.
2. Some of the infrared radiation passes through the atmosphere.
3. Some is absorbed and re-emitted in all molecules.
4. Solar radiation passes through the clear atmosphere
5. Most radiation is absorbed by the earth’s surface and warms it
Infrared radiation is emitted from the earth’s surface

Question 4

1) How is human activity causing global warming?

Answer 4

1) 1. Cutting down forests to create farms or pastures, or for other reasons, causes emissions, since trees, when they are cut, release the carbon they have been storing.
2. Manufacturing and industry produce emissions, mostly from burning fossil fuels to produce energy for making things like cement, iron, steel, electronics, plastics, clothes and other goods.
3. Generating electricity and heat by burning fossil fuels such as coal, oil and natural gas causes a large chunk of global emissions.

Question 5

1) Give 3 examples of pollutants formed by burning fuels?
2) What is a fuel?

Answer 5

1) The major indoor combustion pollutants are carbon monoxide, nitrogen dioxide, sulphur dioxide, fine and ultrafine particles, polycyclic aromatic hydrocarbons (PAHs), formaldehyde.
2) Any substance which upon combustion produces a usable amount of energy is known as fuel. For example wood, coal, biogas, LPG, petrol, diesel etc.

Question 6

1) How do pollutants from burning fuels cause problems?
2) How can we reduce pollutants from burning fuels?

Answer 6

1) When fossil fuels are burned, they release nitrogen oxides into the atmosphere, which contribute to the formation of smog and acid rain. There are three adverse effects of burning fossil fuels: air pollution, water pollution, and climate change
2) Cleaner alternatives, such as dry wood and manufactured solid fuels, produce less smoke and pollution than wet wood or traditional house coal and are cheaper and more efficient to burn. Take public transport or even switch to electric vehicles.

Question 7

1) What is oxidation?
2) What happens when oxygen reacts with metals?
3) What is lost during oxidation?

Answer 7

1) Oxidation is defined as a process in which an electron is removed or transferred from a molecule during a chemical reaction.
2) The metal to corrode (or oxidize) and form the respective metal oxide on the surface
3) There is a loss of electrons

Question 8

1) When a metal oxidises does it gain or loose mass?
2) What ph will a non-metallic oxide be?

Answer 8

1) As long as the object is undisturbed the its weight will increase due to the addition of oxygen molecules
2) This non-metallic oxide when reacted with H2O, form a substance, ‘X’ with pH value less than 7

Question 9

Define fuel

Answer 9

A chemical substance that reacts with oxygen to release stored energy

Question 10

What are two products from burning fuels?

Answer 10

Carbon monoxide and nitrogen dioxide are 2 product from burning fuels