chemistry of water and atmosphere

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Questions and Answers

Which process primarily allows fish and crustaceans to accumulate dissolved oxygen (DO) in aquatic environments?

Photosynthesis in water

Absorption through the skin

Respiration through gills (correct)

Active transport in cells

What is eutrophication commonly characterized by?

Excessive richness of nutrients (correct)

Decreased temperature in water bodies

Increased levels of dissolved gases

Reduction of aquatic life diversity

What is the primary purpose of the desalination process?

To increase salt concentration

To enhance mineral content in drinking water

To remove nitrogen from water

To produce freshwater from saline water (correct)

Which factor directly influences the concentration of dissolved oxygen (DO) in water?

Temperature Signup and view all the answers

What composition percentage of chlorine is found in ocean water?

31% Signup and view all the answers

What is the most abundant element in Earth's atmosphere?

Nitrogen Signup and view all the answers

Which layer of the atmosphere contains the ozone layer?

Stratosphere Signup and view all the answers

What is a major contributor to acid rain?

Sulfuric acid Signup and view all the answers

What process is responsible for converting carbon dioxide into oxygen?

Oxygen Cycle Signup and view all the answers

What percentage of the Earth's surface is covered by freshwater?

3% Signup and view all the answers

How does the density of ice compare to liquid water?

Ice has a lower density Signup and view all the answers

Which of the following best describes adhesion in water?

The attraction of water molecules for other molecules of different kinds Signup and view all the answers

What is the main environmental concern associated with ozone depletion?

Higher ultraviolet radiation exposure Signup and view all the answers

What is the primary characteristic that defines a solution as acidic?

It has more hydrogen ions than pure water. Signup and view all the answers

What is the heat of vaporization of water at its boiling point?

540 cal/g Signup and view all the answers

How is evaporative cooling beneficial to water bodies?

It cools the surface from which it evaporates. Signup and view all the answers

Which of the following accurately describes the term 'buffers' in relation to pH changes?

Buffers can resist changes in pH by donating or absorbing ions. Signup and view all the answers

Which proportion of water on Earth is classified as freshwater?

3% Signup and view all the answers

What is the significance of dissolved oxygen in water bodies?

It is essential for aquatic life. Signup and view all the answers

What is the primary component that distinguishes seawater from freshwater?

Higher salt content. Signup and view all the answers

What role does the pH scale play in characterizing substances?

It indicates whether a substance is acidic or basic. Signup and view all the answers

Study Notes

Atmosphere

The word "atmosphere" comes from the Greek words atmos (steam) and sphaira (sphere)
The atmosphere is a layer of gases that surrounds a planet.
The gravity of the planet holds the atmosphere in place.

Atmospheric Chemistry

Studies the chemical composition of the atmosphere
How matter interacts in the atmosphere
The impact of humans and living things on the atmosphere

Environmental Chemistry
Physics
Meteorology
Computer Modeling
Oceanography
Geology
Volcanology
Engineering

Parts of the Atmosphere

Troposphere:
- Height: 6-20 km
- Weather and climate occur here
- Temperature decreases with height
- Most living things live here
- Most human activities occur here
Stratosphere:
- Height: 11-50 km
- Very dry air
- Temperature increases with height
- Commercial jets and weather balloons fly here
- Polar stratospheric clouds (nacreous clouds) are found here
Mesosphere:
- Height: 50-85 km
- Very dry, similar to the stratosphere
- Temperature decreases with height
- Earth's coldest temperatures occur here (-90°C)
- Difficult to study due to the lack of data
Thermosphere:
- Height: 80-800 km
- Temperature increases with height
- Absorbs X-rays and UV radiation
- Satellites orbit here
Ionosphere:
- Part of the thermosphere (90 km to 500-1000 km high)
- Upper thermosphere
  - Temperature in the upper thermosphere ranges from 500°C to 2000°C+
  - 200°C at daytime
  - 500°C at nighttime
Exosphere:
- Height: >10000 km
- Outermost layer
- Very few molecules, thin
- Boundary between Earth and outer space

History of the Atmosphere

4.7 billion years ago, gases from volcanic activity formed the early atmosphere.
As the Earth cooled, water condensed, and microorganisms developed.
Photosynthesis (by plants) began to convert carbon dioxide into oxygen

Today's Atmosphere

78% nitrogen, 21% oxygen, 0.9% argon, 0.03% carbon dioxide, other gases total of 0.17%

Nitrogen Cycle

Atmospheric nitrogen is converted into usable forms for plants and other living things through various processes like lightning and bacteria
Nitrogen-fixing bacteria in legume root nodules and soil bacteria convert atmospheric nitrogen into ammonia.
This ammonia is then converted to nitrites and nitrates (nitrification) for plant use.
Decomposers (bacteria and fungi) release ammonia back into the soil, completing the cycle.

Oxygen Cycle

Plants take in carbon dioxide during photosynthesis and release oxygen as a byproduct
Animals breathe in oxygen and release carbon dioxide

Photochemical Reactions in the Atmosphere

Initiated by light absorption from the sun
Photoionization: solar radiation ejects electrons from molecules
Photodissociation: photons bombard molecules, breaking them down

Ozone in the Atmosphere

Ozone (O3): found in the stratosphere, layer between 11 and 50 km
Absorbs UV-C and UV-B, thus protecting life on Earth

Ozone Depletion

Ozone depletion is the thinning of the ozone layer
Chlorofluorocarbons (CFCs) are the primary culprits

Acid Rain

Acid rain is caused by sulfuric and nitric acid
Sulfur dioxide and nitrogen oxides react with water in the atmosphere

Dry Deposition

Process where gases and dust particles become acidic

Wet Deposition

Acidic substances fall to the ground mixed in rain, snow, fog, or hail

Measuring Acid Rain

pH scale is used to measure acidity
pH 0-6 is acidic, pH 7 is neutral, pH 8-14 is alkaline