Science 9: Unit 3 - Environmental Chemistry

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Science 9: Unit 3 - Environmental Chemistry

Topic 1.1 - Chemicals in the Environment

The three cycles we learned about in this unit are the Water Cycle, Carbon Cycle, and the Nitrogen Cycle.

The Water Cycle:

Water starts as a liquid in surface water or as water in leaves. Then the water transpires from the leaves and vaporizes from the surface water, becoming water vapour in the atmosphere. Then it condenses into clouds, and water keeps filling up in clouds. Once the clouds are over-filled, water falls in liquid form, called precipitation. The water then drains into surface and groundwater, ready to be evaporated again.

The Carbon Cycle:

Carbon is given off by factories and dead and alive organisms, usually in the form of carbon dioxide. Then the carbon dioxide is absorbed by plants or goes into the soil and slowly forms coal. Then the plant dies and creates more carbon dioxide, ready to be absorbed again.

The Nitrogen Cycle:

Nitrogen gets into the soil through decay and animal waste and then gets rid of bacteria in the roots of plants. It mixes with ammonium and oxygen in the soil. Then it separates and goes back into the atmosphere. To make nitrogen useful, it must be combined with something else, called "Nitrogen Fixation". Nitrogen then goes back into the soil, ready to be used again.

Nitrogen Fixation: Changing free nitrogen so that the atoms can combine with other elements that organisms can use. This happens with lightning.

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Science 9: Unit 3 - Environmental Chemistry

Topic 1.2 - Human Activities and Their Impact

AGRICULTURAL:

Fertilizer: A substance that enriches the soil, allowing plants to grow better. Made up of nitrogen, phosphorus and potassium

Positives:

- Encourages growth

Negatives:

- Too much can damage soil

- Gets into water and damages ecosystems

Pesticides: A chemical used to kill pests(pests harm people, crops, or structures).

Insecticide = Bugs

Herbicides = plants and weeds

Fungicide = Fungus

Positives:

- Kills pests

Negatives:

- Pests can build immunities to overused pesticides

- Cause cancer, poisonous to many other organisms

HUMAN WASTE DISPOSAL

Solid Waste: Garbage taken from anywhere humans are. Some are recycled while most are sent to landfills. In landfills, the waste is burned and then buried into the ground. Sanitary landfills have a clay lining that tops damaging chemicals getting into the soil

Positives:

- Get rid of our waste

Negatives:

- Take up space

- Dangerous chemicals can leak into the soil

- Incinerators cause air pollution

Waste Water: Water that is taken from human places. It can be dangerous if not cleaned. In a rural area, it is taken to a septic tank. In an urban area, it is taken to a sewage treatment plant. Storm sewers take excess rainwater that rolls down the streets can carry dangerous chemicals. Effluent is treated wastewater.

Stages of Cleaning:

Physical - Large material removed

Biological - Bacteria removes smaller material

Chemical - Chemical cleaners are added

Positives:

- Clean water is safe!

Negatives:

- Uncleaned water can pollute the environment, magnifies down the food chain

Fuel Combustion and Industrial Processes: Involve gases reacting to aid us mechanically. Combustion reactions are used to get lots of energy Eg. Gasoline and factories

Positives:

- Transportation, heating and using power are easier

Negatives:

- Lots of CO2 is released

- Causes air pollution

- Acid rain

- Global warming

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Science 9: Unit 3 - Environmental Chemistry

Topic 1.3 - Common Substances Essential to Living Things

Organic Substances: Contain the element carbon, there are more of these. CO2 and CO aren't organic

Inorganic Substances: Do not contain the element carbon

Nutrients are things that we need to live!

Macronutrients: Are needed in large amounts(made of oxygen, carbon, nitrogen and hydrogen)

- Carbohydrates: Provide energy(C, H, O)

- Proteins: Helps us grow and repair(C, H, O, N)

- Lipids: Store energy(C, H, O)

- Nucleic Acids: Found in nucleus

Micronutrients: Are needed in small amounts

- Iron

- Copper

- Many other metals

Nitrogen: Growth and repair in humans and plants

Phosphorus: Growth, bones and photosynthesis

Potassium: Early growth in both, muscles in humans

Magnesium: Photosynthesis, bone composition

Calcium: Muscles and bones, cell wall

Sulfur: Proteins, fruit production

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Science 9: Unit 3 - Environmental Chemistry

Topic 1.4 - The Intake of Substances

Intake In Plants:

Diffusion: Molecules move from high concentration to low concentration in the plant roots

Osmosis: Molecules moving through water through a semi-permeable membrane(high concentration to low concentration)

Active Transport: Movement from low concentration to high concentration using energy

Intake in Animals:

Ingestion: Taking food into the body

Hydrolysis: Using water to break down food(saliva)

Animals can access nutrients on a substrate:

Substrate: The material a substance lives or moves on

Examples:

Algae growing on water(water gives algae nutrients)

- Mold growing on bread

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Science 9: Unit 3 - Environmental Chemistry

Topic 2.1 - Acids and Bases

Acidity: The measure of how many hydrogen ions are in a substance(more ions = more acidic)

pH: On a scale from 0 -14. 0 = acid, 7 = neutral, 14 = base. Use a base-10 system

Acids: Have a pH lower than 7 Eg. Tomatoes, vinegar, battery acid

- Taste sour

- Conducts electricity

Bases: Have a pH higher than 7 Eg. Ammonia, baking soda, shampoo

- Tastes bitter

- Conducts electricity

- Corrodes

Neutralization: Acids and bases will react with each other to form a salt, water and gas Eg. Antacid, vinegar

Acid Indicators: Express the pH of a substance

- Blue Litmus Paper: Turns red when there's an acid

- Red Litmus Paper: Turns blue when there's a base

- Bromothymol Blue: Turns yellow when there's an acid

- Phenolphthalein: Turns red when there's a base

- Universal Indicator: Color = acidity

Effects on the Environment:

Acid Rain: Rain with a pH lower than 5.3. Caused by factory emissions.

- Stops fish eggs

- Slow plant growth

Acid Spring Shock: Acidification of runoff

- Stops fish spawning

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Science 9: Unit 3 - Environmental Chemistry

Topic 3.1 - Monitoring Water Quality

Water quality is determined by what it's used for.

- Human Drinking

- Recreation

- Livestock Drinking

- Irrigation

- Aquatic Life Protection

Biological Indicators: Organisms that live in water and allow us to determine the water quality(some organisms can survive in tougher conditions)

Lots of pollution = Dragonflies, beetles

Little pollution = Mayflies, stoneflies

Inorganic Chemical Factors:

- Dissolved Oxygen: Amount of oxygen in water, more is better

- Temperature

- Turbulence

- Photosynthesis

- # of Organisms

- Acidity: Level of pH

- Heavy Metals: Metals denser than 5g/cm3 are dangerous

- Plant Nutrients: Amount of phosphorus and nitrogen(excess can cause sewage outfalls and fertilizer run-off)

- Nitrates are bad, result from excess fertilizer, etc. Can cause health problems to both humans and aquatic animal diversity

- Excess phosphorus comes from too many algae. It also lowers oxygen levels and sunlight for other plants

- Toxicity: Can cause health problems to organisms

River Diagrams:

Headwaters: Where it starts

Floodplain: Where it overflows too

Mouth: Where it ends

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Science 9: Unit 3 - Environmental Chemistry

Topic 3.2 - Measuring Chemicals in the Environment

LD50: A certain amount of a substance that has a 50% chance of killing you(depends on mass)

Eg, A 2000g rat eats 1500g of LD50, it dies

Examples:

- Caffeine

- Table salt

Parts Per Million: The concentration of chemicals. A ppm(part per million) is a millionth of a substance.

- Part per Billion

- Part per Trillion

Formula: Mass of solute(g, kg)/ total volume of solution(mL, L) x 1,000,000 for ppm(1 B for ppb and 1 T for ppt)

*If poison does damage at ppt, it is very powerful.

Example Problem: Pool has 2,500,000 L of water. 6.75 g of salt is dissolved, what is its ppm?

1. Make sure the units are equivalent(l = kg, mL = g, etc.) They aren't, so convert L to mL: 2,500,000 x 1000 = 2,500,000,000 mL

2. Divide! 6.75 g/ 2,500,000,000 mL = 0.0000000027

3. Multiply! 0.000000027 x 1,000,000 = 0.0027 ppm

Answer: 0.0027 ppm!

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Science 9: Unit 3 - Environmental Chemistry

Topic 3.3 - Monitoring Air and Atmosphere Quality

Air Pollutants:

Sulfur Dioxide: Comes from oil and gas burning, forms acid and causes lung problems

Nitrogen Oxides: Comes from electric utilities, forms acid rain

Carbon Monoxide: Comes from burning carbon, kills organisms

Ground Level Ozone: Comes from overheated ozone layer, causes lung problems

Chlorofluorocarbons: Comes from fridges and aerosal cans, breaks down ozone layer

Atmosphere Quality:

Important Greenhouse Gases:

- Water vapour (H2O)

- Carbon dioxide (CO2)

- Nitrogen oxides (N2O)

- Methane (CH4)

Greenhouse Effect: A naturally occurring event, resulting in greenhouse gases being trapped, making our planet warm and habitable

Enhanced Greenhouse Effect: Higher global temperatures caused by an excess of greenhouse gases

Global Warming: Heat from the sun is trapped by greenhouse gases, caused by human activities. Results in unpredictable climate and ice caps melting. Political opinions on it are that we must charge people on their carbon usage to get them to reduce it.

Technologies to Reduce Impact:

- Scrubbers

- Catalytic converters in cars

- Planting vegetation

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Science 9: Unit 3 - Environmental Chemistry

Topic 4.1 - Transportation of Chemicals Throughout the Environment

Stages to Chemical Movement:

Point Source: Chemical comes from one specific spot

Non-point Source: Chemical comes from a large area

Release: Where the chemicals originate Eg. Littering

Dispersion: Chemicals are spreading out Eg. Wind moving chemicals

Deposition: Where the chemicals end up Eg. Water, Air, or Soil

Transportation of Chemicals in the Air: Chemicals can get anywhere if they can move through the air

Factors:

- Wind speed

- Wind direction

- Mass of chemical

- Weather(rain or snow)

Transportation of Chemicals in Water: Chemicals can move long distances in surface water. Chemicals can increase in concentration in groundwater.

Factors:

- Movement of water

- Temperature of water

- The shape of the waterway(straighter = faster)

- Chemical mass and composition

- Amount of pores

Run-off: Excess water that flows over land surfaces, picking up chemicals as it goes

Transportation of Chemicals in Soil: Chemicals can increase in concentration as they move downwards

Factors:

- Amount of pores

- Composition of soil

- Chemical composition

Biomagnification: The increase in the concentration of a pollutant through the movement of the food chain

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Science 9: Unit 3 - Environmental Chemistry

Topic 4.2 - Reducing the Harmful Chemicals in the Environment

Dilution: Mixing the chemical with lots of air or water to reduce the concentration

Biodegradation: Living things that actively break down waste Eg. Composting

- Temperature

- Soil Moisture

- pH levels (6.5 - 8)

- Oxygen Levels

- Nutrient Availability

Four R's: Reuse, Reduce Recycle, Recover

Phytoremediation: Plants that absorb harmful chemicals

Photolysis: Breaking down compounds using sunlight

Properly cleaning and taking care of chemicals also helps the environment!

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Science 9: Unit 3 - Environmental Chemistry

Topic 4.3 - Viewpoints of Human Activities

Ethical: Is it right to destroy the environment for our needs?

Political: Who has to clean up messes? Will this help the country?

Economic: Is it financially viable to continue supporting the environment?

Environmental: How have our actions changed the environment? Is it all negative?