11.4 How Does The Knowledge Of Chemical Reactions Help Us In Our Daily Lives

Question 1

what does cooking do

Answer 1

heat from cooking soften foods and improves its flavour

it makes it easier for the body to absorb nutrients form food although some nutrients may be destroyed in the process

Question 2

what is decay/decomposition

Answer 2

process of breaking down organic matter into simpler substances

Question 3

how to slow down decay/decomposition of food

Answer 3

vacuum packaging (removes air from packaging prior to sealing -> reduces amt of oxygen in packaging & limits growth of bacteria and other microorganisms

Question 4

ways to prevent rusting (4)

Answer 4

• painting
• oiling
• galvanising (coating iron with a protective layer of zinc)
• drying

Question 5

what pollutants does combustion of fuels produce (3)

Answer 5

• carbon monoxide
• sulfur dioxide
• oxides of nitrogen

Question 6

what is the source of carbon monoxide

Answer 6

burning of fuels in factories and motor vehicles in the presence of insufficient oxygen

Question 7

what is the effect of carbon monoxide

Answer 7

a colourless, odourless and highly toxic gas reduces the amount of oxygen taken up by red blood cells, thus leading to headaches and eventually death due to suffocation

Question 8

what is the source of sulfur dioxide (2)

Answer 8

• burning of sulfur-containing fuels (e.g. coal and petroleum in power stations & factories)
• volcanic eruptions

Question 9

what are the sources of oxides of nitrogen (2)

Answer 9

• burning of fuels at high temperatures in motor vehicles, factories and power stations
• reaction of nitrogen and oxygen in the air during lightning strikes

Question 10

what are the effects of sulfur dioxide and oxides of nitrogen (2)

Answer 10

1. can irritate the eyes, nose and lungs, worsen the symptoms of asthma, heart diseases and respiratory problems (even at low levels)
2. dissolve in rainwater to form acid rain, which harms aquatic life and damages buildings