International Year of Chemistry (IYC) 2011 PowerPoint Pack Quarter One: Environment Water in Our World (W.O.W.) American Chemical Society, Department of Volunteer Support 1-800-227-5558 or e-mail us at [email protected]. Contact us for hands-on activities, contests, local contacts and additional information.
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International Year of Chemistry (IYC) 2011 PowerPoint Pack
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International Year of Chemistry (IYC) 2011 PowerPoint Pack
Quarter One: Environment
Water in Our World
(W.O.W.)
American Chemical Society, Department of Volunteer Support 1-800-227-5558 or e-mail us at [email protected].
Contact us for hands-on activities, contests, local contacts and additional information.
American Chemical Society
Wondering About Water
Interesting facts about Water
Over 70% of the Earth’s surface is covered with this liquid (oceans, rivers, lakes, etc.)
The second most common form of water on Earth is ice (if all the ice melted – the sea-level would rise by 70 meters)
Water is essential for life (most animals and plants contain more than 60% water by volume).
Less than 1% of all water on Earth is available or clean enough for humans to drink. The rest is salty or frozen.
Some of Water’s Physical Properties
Boiling Point = 100 C (212 F) at 1 atmosphere of ⁰ ⁰pressure
Freezing Point = 0 C (32 F) at 1 atmosphere of ⁰ ⁰pressure
One atom of oxygen (O) is bound to two atoms of hydrogen (H) to form a 105 angle “V” shape.⁰
Both H atoms are attached to one side of the O atom.
This results in a molecule with a slight positive charge on one side of the molecule (H) and a slight negative charge on the other side (O) – this is called a dipole moment.
Thus, water molecules tend to attract each other by a process called Hydrogen-Bonding - this gives water many unique properties.
Hydrogen Bonding – creates attraction between water molecules
Water contracts until it reaches 4 C . Then it expands ⁰until it is solid.
The density of ice (0.915 g/cc) is less than that of liquid water (0.9999 g/cc) at 0 C.⁰
Its density at 4 C is 1.000 g/cc.⁰ This is why ice floats – if it didn’t, oceans, lakes, etc.
would freeze from the bottom up and remain frozen – Earth would be a completely different planet - maybe uninhabitable by humans.
American Chemical Society
Water Matters
Overview The amount of available water has not changed for
thousands of years.
Water is essential to the environment, human life, and industry.
Approximately 1 billion people in over forty countries are currently under a water crisis.
The increasing world population and the demand for better livelihoods globally, will continue to contribute to a worsening water crisis.
Source: World Bank “Water and Development” Executive Summary, May 2010
Scarcity of Resource Each year millions of people die from diseases
associated with inadequate water supply, sanitation and hygiene.
Four of every ten people in the world do not have access to adequate sanitation.
Two of every ten people have no source of safe drinking water.
According to the United Nations World Water Development Report, by the year 2050, at least one in four people is likely to live in a country affected recurring shortages of freshwater.
Pollution Pollution refers to the introduction of harmful substances or products into
the environment.
Major water pollutants include microbes, nutrients, heavy metals, organic compounds, oil, sediments and heat (thermal pollution*). * Thermal pollution is typically the industrial release of heated water into a river, lake, or other body of water, causing a rise in temperature that endangers aquatic life
Pollutants are usually the cause of extremely dreadful water quality conditions around the world..
Source: World Water Development Report 3 'Water in a Changing World'
http://www.un.org/waterforlifedecade/quality.html
Analyzing Water
Depending on its use, water may have a variety of conditions for composition and purity.
Types of analysis vary from simple field testing to determine a single property to laboratory based multi-property analysis.
Some basic water quality measurements include pH, Acidity, Alkalinity, electrical conductivity, and water hardness. The pH of water measures its hydrogen ion concentration and
indicates whether the sample is acidic, neutral or basic.
Acidity of water measures its capacity to react with strong base to a designated pH.
Alkalinity measures the acid-neutralizing capacity of water. It is attributed to the presence of hydroxide, carbonate, and bicarbonate ions.
American Chemical Society
Water: Getting It Clean, Keeping It Clean
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Potable Water and Its Importance
Water is considered potable if it is safe for drinking and food preparation.