Chapter 5: The Water We Drink

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Chapter 5 The Water We Drink

• Water, water, every where, And all the boards did
  shrinkWater, water, every where, Nor any drop
  to drink.
• And every tongue, through utter drought, Was
  withered at the root We could not speak, no more
  than if, We had been choked with soot. The Rime
  of the Ancient Mariner -Samuel Taylor Coleridge
  -
• We shall not finally defeat AIDS, tuberculosis,
  malaria, or any of the other infectious diseases
  that plague the developing world until we have
  also won the battle for safe drinking-water,
  sanitation and basic health care. -Kofi Annan-
  Preface International Decade for Action Water
  for Life 20052015 An advocacy guide

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Chapter 5 The Water We Drink
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• Bottled Water Quiz
• True or False?
• 1. Bottled water is healthier than tap water.
• 2. Bottled water is safer than tap water.
• 3. Bottled water is convenient and portable.
• 4. Most plastic water bottles are recycled.
• 5. The market for bottled water is growing.
• 6. The UN is addressing water issues in the
  developing world.
• 7. Some bottled water is more expensive than
  gasoline.
• My purchase of bottled water is unrelated to
  safer drinking water for the whole world.
• http//www.prcweb.org/DOCS/waterbrochureFINALPARTN
  ERS.doc

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• 1. False. There is often no difference. Little is
  known about the health risks of water stored in
  disposable plastic (PET) bottles or the effect of
  additives over long periods at high
  temperatures.
• 2. False. The US EPA sets more stringent
  standards for tap water than the FDA does for
  bottled beverages. Roughly 40 of bottled water
  is actually tap water.
• 3. True. But using a refillable bottle is just as
  convenient and less expensive.
• 4. False. According to the Container Recycling
  Institute, only 14 of PET bottles are recycled.
  The rest end up in landfills or as litter.
  Millions of barrels of oil are required each year
  to produce and transport them.

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• 5. True. The Beverage Marketing Corporation
  states that Americans spent more than 9 billion
  on bottled water in 2004 and that the products
  rate of growth was almost 10 per year for the
  previous 10 years.
• 6. True. The UN adopted a resolution in 2003
  calling this the Decade for Water. The
  Millennium Development Goals also have an
  objective to halve the number of people who lack
  reliable and safe drinking water by 2015.
• 7. True. Often selling for up to 2.50 a liter
  (which translates to 10 a gallon), bottled water
  is more expensive than gasoline.
• 8. False. The UN estimates that if the world took
  half of what it now spends on bottled water (100
  billion per year) and invested it in water
  infrastructure and treatment, everyone in the
  world could have access to clean drinking water.

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Chapter 5 The Water We Drink

• Forum Says Governments Must Improve Tap Water,
• Bottling companies declare it a non-issue
• Clean Water as a Human right
• 6000 people a day die because of poor water
  quality
• UN committee on water-
• Bottled water more valuable than crude oil

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Chapter 5 The Water We Drink

• World wide concerns Quality of water
• Sanitation
• contamination
• natural contaminants
• Privatization of water service
• Pay Actual Costs
• Clean water projects for developing nations
  helps eliminate poverty and hunger
  www.globalwater.org/

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5.3
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Where Does Potable (fit for consumption)
Drinking Water Come From?
Surface water from lakes, rivers,
reservoirs Ground water pumped from wells
drilled into underground aquifers
5.2
10
What we need to know to talk about water

• Where we find water
• Physical properties of water
• What Solutions are
• How we measure concentrations of solutions
• Ionic compounds
• Covalent compounds
• the difference between polar and non polar
  compounds

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Chapter 5 The Water We Drink

• Definitions
• Aquifers Pools of water trapped in sand and
  gravel 50-500 ft below the surface

Hans Hillewaert (Lycaon)
- Ground water Water pumped from aquifers
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Chapter 5 The Water We Drink

• Definitions
• Surface water Lakes rivers and reservoirs

National Park service
Sansculotte
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Classifying Matter
All Matter
NO
Can it be separated by a physical process?
YES
Pure Substances
Mixtures
NO
YES
YES
NO
Can it be broken down into simpler ones by
chemical means?
Homogeneous at the macroscopic level
Elements
Heterogeneous Mixtures
Compounds
Solutions
1.6
14
A solution is a homogeneous mixture of uniform
composition. Solutions are made up of solvents
and solutes.
Substances capable of dissolving other
substances- usually present in the greater amount
Substances dissolved in a solvent- usually
present in the lesser amount
When water is the solvent, you have an aqueous
solution.
5.3
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How pure is your water
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Concentration Terms
Parts per hundred (percent) Parts per million
(ppm) mg/L Parts per billion (ppb)mg/L
20 g of NaCl in 80 g of water is a 20 NaCl
solution
5.4
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Molarity M moles solute
liter of solution
concentration of
1.0 M NaCl solution NaCl 1.0 M 1.0 mol
NaCl/L solution Also this solution is 1.0 M in
Na and 1.0 M in Cl- Na 1.0 M and Cl-
1.0 M
5.4
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What is the concentration (in M and mass ) of
the resulting solution when you add 5 grams of
NaOH to 95 mL of water?
95 mL H2O 95 g H2O 5 g NaOH/100 g
solution 95 mL H2O .095 L 5 NaOH 1.3 M
solution of NaOH
5.4
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What is the molarity of glucose (C6H12O6) in a
solution containing 126 mg glucose per 100.0 mL
solution?
6.99 x 10-3 M
5.4
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How to prepare a 1.00 M NaCl solution
mol solute
M
L of solution
Note- you do NOT add 58.5 g NaCl to 1.00 L of
water. The 58.5 g will take up some volume,
resulting in slightly more than 1.00 L of
solution- and the molarity would be lower.
5.4
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Different Representations of Water
Lewis structures
Space-filling
Charge- density
Region of partial negative charge
Regions of partial positive charge
Charge-density
5.5
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Electronegativity is a measure of an atoms
attraction for the electrons it shares in a
covalent bond
EN Values assigned by Linus Pauling, winner of
TWO Nobel Prizes
On periodic table, EN increases
5.5
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A difference in the electronegativities of the
atoms in a bond creates a polar bond.
O
H
H
A polar covalent bond is a covalent bond in which
the electrons are not equally shared, but rather
displaced toward the more electronegative atom.
Partial charges result from bond polarization
5.5
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H2 has a non-polar covalent bond.
Water molecule is polar due to polar covalent
bonds and the shape of the molecule.
NaCl
NaCl has an ionic bond-look at the EN
difference. Na 1.0 Cl 2.9 DEN 1.9
5.5
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Polarized bonds allow hydrogen bonding to occur.
A hydrogen bond is an electrostatic attraction
between an atom bearing a partial positive charge
in one molecule and an atom bearing a partial
negative charge in a neighboring molecule. The H
atom must be bonded to an O, N, or F
atom. Hydrogen bonds typically are only about
one-tenth as strong as the covalent bonds that
connect atoms together within molecules.
Hbonds are intermolecular bonds. Covalent
bonds are intramolecular bonds.
5.6
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When ions (charged particles) are in aqueous
solutions, the solutions are able to conduct
electricity.

• Pure distilled water (non-conducting)
• Sugar dissolved in water (non-conducting) a
  nonelectrolyte
• NaCl dissolved in water (conducting) an
  electrolyte

5.7
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Substances that will dissociate in solution are
called electrolytes.
Ions are simply charged particles-atoms or groups
of atoms. They may be positively charged
cations, Or negatively charged- anions.
Dissolution of NaCl in Water
The polar water molecules stabilize the ions as
they break apart (dissociate).
5.8
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Ions that are themselves made up of more than one
atom or element are called polyatomic ions.
NaSO4 (sodium sulfate) dissociates in water to
form
The sulfate group stays together in solution.
Na
and
Sodium ions
Sulfate ions
5.7
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Simple generalizations about ionic compounds
allow us to predict their water solubility.
5.7
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Maximum Contaminant Level Goal (MCGL) and
Maximum Contaminant Level (MCL)
5.10
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Hard water contains high concentrations of
dissolved calcium and magnesium ions. Soft water
contains few of these dissolved ions.
A pipe with hard-water scale build up
5.12
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Because calcium ions, Ca2, are generally the
largest contributors to hard water, hardness is
usually expressed in parts per million of calcium
carbonate (CaCO3) by mass. It specifies the mass
of solid CaCO3 that could be formed from the Ca2
in solution, provided sufficient CO32- ions were
also present Ca2(aq)  CO32(aq) ?
CaCO3(s) A hardness of 10 ppm indicates that
10 mg of CaCO3 could be formed from the Ca2 ions
present in 1 L of water.  
5.7
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Access to safe drinking water varies widely
across the world
5.14
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Two water purification techniques
Reverse osmosis
Distillation
5.14