Unit C Section 1.1 Flashcards
What are elements?
Elements are pure substances that cannot be broken down into other substances.
What do elements form?
They form chemical compounds that are used and
reused by living things.
Why is nitrogen important for living things.
plants require nitrogen to make substances necessary for life
How is nitrogen taken in plants?
plants can use nitrogen only when it is combined with other elements, such as hydrogen and oxygen
It has to be “fixed” in compounds with
other elements
How much nitrogen is in the air?
is about 78% nitrogen in the form of nitrogen gas (N2(g))
What is Nitrogen fixation?
is the process of changing free nitrogen so
that the nitrogen atoms can combine with other elements to form compounds that organisms can use.
What does most of the nitrogen fixation in soil?
Certain types of bacteria do most of the nitrogen fixation in the soil.
How do bacteria do nitrogen fixation in the soil?
- Some of these bacteria are located in the root nodules of specific types of plants, such as beans, clover, and alfalfa
- The bacteria in these nodules are able to separate the two nitrogen atoms that form nitrogen gas (free nitrogen).
- Once separated, the nitrogen atoms can form compounds with other elements, such as hydrogen and oxygen.
What can also fixate nitrogen in the air?
Lightning also converts nitrogen in the air to nitrogen compounds that plants can use.
What are nodules?
The bumps on the roots of this alfalfa plant are called “nodules.”
What are steps in the nitrogen cycle?
- After nitrogen fixation occurs, plants use the nitrogen-containing compounds
- Animals then eat the plants.
- Their bodies use the nitrogen in the compounds to make more complex substances, such as proteins.
- Decomposers break down these large nitrogen-containing molecules in dead organisms and animal waste into simpler nitrogen compounds in the soil.
- The nitrogen can move from organisms and back to the soil several times.
- Eventually, some nitrogen-containing compounds are broken down further by other bacteria in the soil.
- This nitrogen is released back into the air as free nitrogen, and the cycle begins again.
Is the concentration of nitrogen the same everywhere?
-the concentration of usable nitrogen is not the same everywhere.
How is nitrogen removed from local environments in different ways?
-Conversion to free nitrogen by bacteria is one way
-by water carrying dissolved nitrogen compounds
away from or deep in to the soil so that they are unavailable to plants
-by water carrying dissolved nitrogen compounds
away from or deep into the soil so that they are unavailable to plants
What do farmers do if the soil lacks nitrogen?
If the soil lacks nitrogen, farmers plant nitrogen-fixing plants such as clover and alfalfa or add fertilizers to
increase the amount of nitrogen
The process of cellular respiration?
-You give it food as “fuel” and air rich in oxygen
-It uses the chemicals in the food and the oxygen in
the air in the process of cellular respiration to give you energy
-One of the products you release in this process is carbon dioxide
the vehicle burns fuel such as gasoline or
propane process?
- Oxygen from the air is required for that reaction.
- Along with the energy produced in this combustion reaction, gases such as water vapor, carbon dioxide, carbon monoxide, and nitrogen oxides are released into the atmosphere.
What is Pollution?
Pollution is any change in the environment that produces a condition that is harmful to living things.
For example, smog caused by vehicle exhaust emissions.
-Forest fires
What happens to the concentration of chemicals that is left in the environment through man-made activities:
- Many of these chemicals can be broken down through natural processes.
- Other chemicals cannot be broken down easily and can cause long-term problems
what is an issue?
An issue is any subject of importance about which people have strong, conflicting points of view
What is a fertilizer?
A fertilizer is a substance that enriches soil so that plants will grow better.
Fertilizers are described by the major nutrient elements they contain.
Which are:
These elements are nitrogen, phosphorus, and potassium.
15–30–15
What can be the fourth element in the fertilizer?
Some fertilizers have a fourth number and the letter “S” on the label to indicate that they contain sulfur as a major ingredient.
What are the two types of fertilizers:
Fertilizers may come from natural sources or synthetic chemicals.
What is the disadvantage of fertilizer?
Too much fertilizer may even damage the crop it’s supposed to help.
What are Pesticides?
Pesticides are chemicals used to kill pests
What is a pest?
A pest is an organism that harms people, crops, or structures.
-Pesticides are grouped according to the pest that they kill.
Herbicides
Herbicides kill or control weeds.
Insecticides
Insecticides kill or control insects.
Fungicides
Fungicides kill fungi.
What would happen if pesticides were not used?
It is estimated that at least 50% of the world’s food production would be lost to pests
What are the disadvantages of pesticides?
- pesticides can be harmful to people and other non-pest organisms.
- they kill both pest and non-pest species.
- Another problem occurs with pesticides that stay in the environment for a long time
How can some chemicals be introduced to the environment?
Chemicals may be introduced into the environment when we dispose of solid waste or wastewater.
What can solid waste include?
Solid waste includes the garbage that is collected from households, industrial plants, commercial buildings, institutions, and construction and demolition sites. It includes large items, such as machinery, all the way down to small items, such as the caps on plastic drink bottles.
Where does the solid waste go?
Some solid waste can be reused or recycled, but most of it is placed in landfill sites
What are incinerators?
Some hazardous wastes are burned in special plants called incinerators, which burn at very high temperatures.
Emissions from incinerators may contribute to air pollution
Sanitary landfill sites
-Sanitary landfill sites are specially built to prevent waste chemicals from moving into the soil.
-As rainwater or groundwater moves through
solid waste, can dissolve or corrode some items
-Sanitary landfills use plastic liners and compacted clay to prevent these solutions from entering the soil and the groundwater.
sewage
Wastewater containing dissolved and undissolved materials from your kitchen, bathroom, and laundry is called sewage
-Sewage moves through pipes into a septic tank in rural areas or to a sewage treatment plant in towns and cities
septic tank
-A septic tank is an underground container where
bacteria break down the organic materials before they are moved out to the soil.
sewage treatment plant
A sewage treatment plant treats wastes from homes, businesses, industries, and institutions.
effluent
Treated wastewater or effluent is released into rivers or lakes. It may contain nitrogen and phosphorus from the breakdown of sewage during treatment.
storm sewers
-If the municipal sewage system cannot handle a large quantity of rainwater from street drains, that water may go directly into a river or lake through large pipes called storm sewers
fossil fuels
Coal, oil, and natural gas are called fossil fuels because they formed from dead plants and animals
What does water from storm sewers contain?
Water from storm sewers contains chemicals washed off the street, such as oil or other fluids that have leaked from vehicles, and salt from snow-clearing operations.
Why are fossil fuels called hydrocarbons?
They are called hydrocarbons because they are
mainly made up of the elements hydrogen and carbon
They may also contain oxygen, nitrogen, and sulfur. Fossil fuels may contain traces of other elements such as mercury and lead.
What do fossil fuels produce when they are burned:
When fossil fuels are burned in homes, vehicles, and industrial plants, they produce large amounts of carbon dioxide and water vapor.
The combustion of fossil fuels may also release pollutants such as sulfur dioxide, nitrogen oxides, and traces of mercury and lead into the air
What is the formula for combustion reaction?
hydrocarbon + oxygen → carbon dioxide + water + energy
The equations below show what happens in the combustion of methane (in natural gas)
methane + oxygen → carbon dioxide + water vapour + energy
The equations below show what happens in the combustion Propane.
( is used in barbecues, vehicles, and some home appliances.)
propane + oxygen → carbon dioxide + water vapour + energy
What was coal used before and now?
At one time, coal was also used in homes as heating fuel.
Today it is used mainly for electrical generation.
What is natural gas composed of?
Natural gas is composed of compounds such as methane, ethane, propane, and butane. It also contains nitrogen gas, carbon dioxide, hydrogen sulfide, helium, and traces of metals such as
mercury.
What is the purpose of natural gas?
Natural gas is processed to separate its components for different uses. Methane, propane, and butane are all derived from natural gas and are used primarily for heating. Ethane is used in plastics such as
polyethylene.
Natural gas is also processed to eliminate unwanted substances such as hydrogen sulfide, a poisonous chemical.
What is sour gas?
Natural gas that contains hydrogen sulfide is called “sour” gas
What is sweet gas?
Natural gas that does not contain hydrogen sulfide.
What does the process for removing hydrogen sulfide produce?
produces sulfur dioxide
gas and pure sulfur
Sulfuric acid is used for what?
Sulfuric acid is used in making fertilizers,
steel, synthetic fibers, and paints.
