chap 11 how does chemical changes help us in our daily lives?

Question 1

Cooking

Answer 1

(+) softens food and improves flavour
(+) makes it easier for body to absorb nutrients

Question 2

respiration

Answer 2

(+) releases energy for the cell to survive and reproduce

Question 3

decomposition, and how do you prevent it.

Answer 3

(+) allows nutrients to be returned to the environment as fertilizer
(-) causes food to spoil, and eating spoilt food is harmful to health

*vacuum packaging can remove air (oxygen) from the package, limiting growth of bacteria and other microorganisms.

Question 4

rusting and how to prevent it

Answer 4

(-) occurs rapidly in humid climates, due to the large amount of water vapour in the air

*rusting can be prevented by preventing iron or steel objects from coming into contact with water or oxygen by:
1. painting
2.oiling
3.galvanishing ( coating iron with protective layer of zinc )
4. drying

Question 5

combustion

Answer 5

(-) releases carbon dioxide, which contributes to global warming and ocean acidification
(-) produces air pollutants such as carbon monixide, sulfur dioxide and oxides of nitrogen
(+) produces energy for food/ petrol

Question 6

what are the sources and effects of carbon monoxide?

Answer 6

source: incomplete combustion of fuels

effects: reduces the amount of oxygen taken up by red blood cells, resulting in headaches and eventually death.

Question 7

what are the sources and effects of sulfur monoxide

Answer 7

source: burning of sulfur- containing fuels such as coal

effects:
- can irritate eyes, nose and lungs
- worsens symptoms of asthma, heart diseases and respiratory problems
- dissolve in water to form acid rain, which harms aquatic life and damages building
( same goes for oxides of nitrogen )

Question 8

what are the sources and effects of oxides of nitrogen

Answer 8

sources: burning of fuels at high temperatures and lightening strikes

effects:
- can irritate eyes, nose and lungs
- worsens symptoms of asthma, heart diseases and respiratory problems
- dissolve in water to form acid rain, which harms aquatic life and damages building
( same goes for oxides of nitrogen )

Question 9

acidification of oceans

Answer 9

(-) carbon dioxide in the atmosphere dissolves in seawater to form carbonic acid, making the ocean more acidic over time.
(-) shells and skeletons marine organisms such as oyster and corals contain calcium carbonate, which are broken down as they react with acidic seawater
(-) organisms in oceans are unable to survive under conditions of a lower pH