1.1 - Chemicals in the Environment

Question 1

Which living things depend on and are made up of chemicals to survive?

Answer 1

All of them

Question 2

Provide examples of some chemicals produced by nature that are harmful

Answer 2

• Ex. CO2, SO2, ash from volcanoes

Question 3

Provide examples of some chemicals used by humans that are harmful

Answer 3

• Ex. Pesticides

Question 4

Provide examples of some elements that cycle through ecosystems

Answer 4

• Ex. Carbon, oxygen, nitrogen and phosphorus

Question 5

What percent of the air is ‘free’ nitrogen (N2(g))?

What is free nitrogen?

Answer 5

78% of the atmosphere is “free” N2(g) (unusable for most organisms)

Question 6

What type of nitrogen do plants require?

Answer 6

Plants require “fixed” nitrogen: nitrogen incorporated into compounds through nitrogen fixation

Question 7

How can nitrogen be fixed?

Answer 7

• Some bacteria on the roots of plants fix nitrogen in the soil
• Lightning can also fix nitrogen

Question 8

Provide some examples of processes and activities that affect environmental chemicals

Answer 8

• Ex. Natural: Cellular respiration releases CO2

- Ex. Human activity: Vehicles release CO2 and other gases when they burn fuel

Question 9

What is pollution? What are some examples of pollution?

Answer 9

• Pollution is a change in the environment that causes harm to living things
  
  • Ex. Smog makes it difficult to breath

Question 10

How do agricultural activities affect environmental chemicals?

Answer 10

Fertilizers:

• Enrich soil, improve plant growth
• The label has 3 numbers on it, each of which indicates the percentage of nitrogen, phosphorous and potassium, respectively.
  
  • Ex. 15-30-15
• A 4th number with “s” may be used for sulfur
• Can be natural or synthetic (both harmful if overused)

Pesticides:

• Chemicals used to kill pests (includes herbicides, insecticides, fungicides)
• Can stay in the environment for a long time
• Some are not selective: they kill non-pests
• Pests can become resistant

Question 11

How do solid wastes affect environmental chemicals?

Answer 11

Solid Wastes:

• We generate a large amount of garbage
• Most is placed in landfills
• Some is burned in incinerators (air pollution)
• Some can be recycled or reused
• Sanitary landfills have plastic liners and clay to -prevent leakage

Question 12

How does waste water affect environmental chemicals?

Answer 12

Wastewater:
Sewage - Waste water produced by humans
Septic Tanks - Used in rural areas
Sewage Treatment Plants - Used in urban areas
Effluent - Treated wastewater, released into rivers and lakes
Storm Sewers - Transports rain water directly to rivers or lakes in some places
- This water often contains chemicals or oils from the street

Question 13

How does fuel combustion affect environmental chemicals?

Answer 13

Fossil Fuels:
- Form from dead plant/animal materials
- Hydrocarbons (contain H and C), but may contain other elements
- Other pollutants may be released as well, such as traces of lead
- Ex. Used for heating, electricity + cars
- Ex. Coal, oil, natural gas
- Burning methane/fossil fuel:
CH4(g) + 2O2(g) → CO2(g) + 2 H2O (g) + Energy

Question 14

How do industrial processes affect environmental chemicals?

Answer 14

Industrial Processes:

• Can release pollutants such as sulfur dioxide or nitrogen oxides
  
  • Ex. Natural gas contains several hydrocarbons and other pollutants. During processing:
• Natural gas is separated into different products with different uses
• Unwanted substances are often removed, such as poisonous hydrogen sulfide (if present: sour gas, if absent: sweet gas). This releases sulfur dioxide into the air