1B. Looking at Water

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1B. Looking at Water Its Contaminants

• Learning more about the chemistry of water and
  how substances interact with water

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Do Now

• The teacher has two substances on the desk (A and
  B). Are they the same? Venture a guess as to what
  you think they are.
• Explain why beetles have the ability to walk on
  water. (Take a look at the picture below)

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Objectives

• SWBAT
• Learn the physical properties of water compare
  to another liquid.
• Use a balance
• Read a grad. cylinder
• Make and record measurements
• Record observations

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Water has Physical Properties

• Matter can be distinguished by its properties.
• Physical properties are those that can be
  observed and measured without changing the
  chemical makeup of the substance
• Can you think of some?
• Write down at least 3 physical properties of
  water that you can think of.

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Physical Properties of water

• Color colorless, clear
• Odor - odorless
• Density mass/ volume
• Temperature dependent
• Freezing point 0C
• Boiling point 100C
• Surface tension

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Pure Water

• Pure water is water with absolutely nothing
  else dissolved or suspended in it
• Properties of pure water
• Clear
• Colorless
• Odorless
• Tasteless

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Lab Demo

• Make and record proper observations for each
  demonstration.

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Do Now

• Draw a graduated cylinder, with the appropriate
  volume markings and layer the liquids according
  to density.
• 5 mL liquid A, Density 3.4g/ml
• 2 ml liquid B, Density 0.90/ml
• 3 ml liquid C, Density 1.00g/ml

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Do Now

• What physical property of water explains the
  sheeting action under the swimmers right arm?

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Objectives

• SWBAT compare and contrast surface tension
  between water and alcohol
• SWBAT define matter and discuss the physical
  properties of water.
• SWBAT calculate density

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Surface Tension
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Surface Tension

• Forces of attraction between the hydrogen atoms
  in water that keep the atoms close together
• Almost as if they form a barrier and make the
  water molecules stick together
• Held together by cohesive forces.
• Responsible for creating a meniscus
• Responsible for spherical water drops
• Doesnt stick to wax (on cars etc.)Adheres
  weakly, so molecules stick together.

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Molecular view of surface tension
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HW

• Pg 50 (1-4)

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Do Now

• Draw
• A) a water molecule (H2O)
• B) 2H2O

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Objectives

• SWBAT identity the number of different compounds
  in a substance or mixture
• SWBAT draw different mixtures and answer
  questions related to those pictures

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Particulate Level

• To understand the macroscopic (large scale
  readily observed) properties of water, you have
  to understand waters behavior at the particulate
  level the level of small particles the level
  of atoms and molecules

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Substances

• Atoms building blocks of matter
• Elements made of one kind of atom
• Represented by symbols (H, O, Ne) sometimes
  formulas (H2, O2)

• Molecules made of atoms joined together atoms
  can be the same or different
• Compounds made of different elements combined
  together
• Represented by formulas (H2O, KCl)

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MODELSREPRESENTATIONS OF ATOMS MOLECULES

• These pictures are one kind of model (space
  filling model).

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Drawing Models

• Sample Problem Draw a model of two gaseous
  compounds in a homogeneous mixture.
• What do you need to know to draw your model?
• What is a homogeneous mixture?
• What might a gaseous compound look like?
• How many compounds are in this mixture?
• There is more than one drawing possible.

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Practice

• Describe the picture
• 1. What type of mixture is this?
• 2. How many compounds?
• 3. What state of matter?

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Drawing Models

• Which of the following drawings best represents a
  homogeneous mixtures of two gaseous compounds?

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Drawing Models

• The best answer is b.

• 2 types of molecules are uniformly mixed
• Atoms are colored to represent different elements

• Not homogeneous

• 3 different compounds, not 2

b c are space-filling models. a is a
ball-and-stick model. Both are acceptable.
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Drawing Models

• Work in pairs on WKST U1B.5- Modeling Matter

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Do Now

• What is a solution?
• Describe the difference between a heterogeneous
  and homogeneous mixture

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Objectives

• SWBAT review the differences between types of
  mixtures.
• SWBAT create a concept chart of substances and
  mixtures and provide examples of each.
• SWBAT differentiate between symbol, element,
  compound, and molecule.

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Matter

• MATTER IS ANYTHING THAT HAS MASS OCCUPIES
  SPACE.
• WATER IS MATTER.

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A. Matter Flowchart
MATTER
yes
no
Can it be physically separated?
Homogeneous Mixture (solution)
Heterogeneous Mixture
Compound
Element
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Substances Dissolve in Water

• Aqueous solutions water based solutions
• SOLUTE- substance that is being dissolved
• SOLVENT- substance that dissolves the solute
  (usually water, in aqueous solutions it is water)

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Solutions

• All solutions are homogeneous mixtures
• A solute dissolves in a solvent to make a
  solution
• Solutions are clear but not
  necessarily colorless
• A conductivity test indicates the
  presence of dissolved charged
  particles

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Substances Dissolve in Water
Sample Solute Solvent
Salt Water
Coffee
lemonade
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Matter is divided into a mixture or a substance

• Substance
• Definite composition, not physically able to
  separate
• Mixture
• two or more substances coming together but
  keeping their individual properties
• Foul Water was a mixture of water, used coffee
  grinds, oil, garlic powder, salt

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Types of Mixtures

• Homogeneous Mixture
• Composition is the same or uniform throughout
• Heterogeneous Mixture
• Composition is not the same or uniform throughout.

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2 Types of Heterogeneous Mixtures

• Suspension heterogeneous mixture containing
  large, solid particles that can settle out or be
  separated by filtration

• Colloid heterogeneous mixture containing
  particles too small to settle out cloudy
  Tyndall effect

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Types of Substances

• Elements
• One type of atom
• Compounds
• Two or more types of atoms chemically bonded
  together

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A. Matter Flowchart

• Examples
• graphite
• pepper
• sugar (sucrose)
• paint
• soda

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A. Matter Flowchart

• element
• hetero. mixture
• compound
• hetero. mixture
• solution

• Examples
• graphite
• pepper
• sugar (sucrose)
• paint
• soda

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Mixtures(variable composition)

• Homogeneous Solutions
• evenly distributed

• Heterogeneous
• not evenly distributed

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Diatomic Elements

• Hydrogen
• Nitrogen
• Oxygen
• Fluorine
• Chlorine
• Bromine
• Iodine

• There are 7 diatomic elements
• These atoms are never alone, if they are the pair
  up with the same atom

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C. Mixtures

• colloid
• suspension
• colloid
• solution
• suspension

• Examples
• mayonnaise
• muddy water
• fog
• saltwater
• Italian salad dressing

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Do Now

• Fill in table on
• worksheet Unit1B4,69

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Objectives

• Distinguish between symbols, chemical formulas
  and equations
• Determine the number of protons, electrons and
  neutrons in an atom

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Symbols, Formulas, Equations

• The international language of chemistry includes
  symbols, formulas, equations.
• Symbols are like letters.
• Formulas are like words.
• Equations are like sentences.

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The lettersSymbols Elements

• Elements are organized on the Periodic Table of
  Elements
• Each element is represented by a symbol
• Capital letter
• Capital letter lower case letter
• Find some of these symbols on the Periodic Table.

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The Periodic Table of Elements contains much more
useful information than just symbols.You will
be learning more about this table throughout this
course.

• People use aluminum to make a variety of
  products, including foil, cans, lightweight
  construction materials.

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• Silicon has properties that lie between those of
  metals and nonmetals. It is classified as a
  metalloid. One of its primary uses is in
  electronic devices.

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• Sulfur is a nonmetal used in products such as
  fungicides and rubber of automobile tires.

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The wordsFormulas

• Formulas represent specific chemical substances.
• Formulas are made of symbols.
• Formulas may include subscripts.
• A subscript refers back to the symbol immediately
  before it. A 1 is understood not written.

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Examples

• CO
• 1 carbon 1 oxygen
• CO2
• 1 carbon 2 oxygens
• NH3
• 1 nitrogen 3 hydrogens
• H2O
• 2 hydrogens 1 oxygen
• H2SO4
• 2 hydrogens, 1 sulfur, 4 oxygens

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Diatomic Elements

• Most elements exist as individual atoms and are
  represented with symbols.
• Some elements exist as 2 bonded atoms of the same
  element.
• For example, hydrogen is a diatomic gas, so is
  always written as H2 when it is an uncombined
  element.

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The sentencesEquations

• Equations give the details of chemical reactions
• Chemical reactions involve the breaking making
  of chemical bonds, causing atoms to be rearranged
  into new substances.
• The new substances have different properties from
  those of the original materials.

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The sentencesEquations

• The original substances (reactants) are written
  first. Then, an arrow points to the new
  substances that are made (products).
• reactants ? products
• hydrogen oxygen ? water
• 2H2 O2 ? 2H2O
• Note that this equation is balanced.
• The total number for each kind of atom is the
  same for both reactants products.

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Oxygen

Element Symbol
Atomic Number
(Oxygen)
(number of protons) (and number of electrons if
neutral)
Atomic Mass
(number of protons and neutrons)
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Practice Problems
Complete the missing information and include the
number of protons, neutrons, and
electrons.Worksheet- Unit 1 B.7 part 2- Using
the Periodic Table
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Complete

• Worksheet Unit1B7
• Worksheet Unit1B7 part 2

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HW

• Pg 50-51 (5-18)

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Do Now

• Pg 51 (19-20)
• Complete the table below

Element/ Name Atomic Number Atomic Mass protons electrons neutrons
Na ________
W ________
Au ________
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Objectives

• SWBAT draw out Lewis Diagrams of different atoms
• SWBAT identify ions as cations and anions and be
  able to determine the formula for ions and be
  able to name them.
• SWBAT work in groups to answer questions as a
  conclusion to activity

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Parts of the Atom

• Proton-
• In nucleus, positive charge and a mass of 1
• Neutron-
• In nucleus, neutral charge and a mass of 1
• Electron-
• Outside nucleus, negative charge and no mass

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Complete the chart
Part of Atom Charge Mass
Proton
Neutron
Electron
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So if this is an atom

• What makes atoms different?
• How is carbon different from oxygen?
• Different numbers of protons

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Rubbing a balloon against your hair results in
static electricity.Clothes taken out of the
drier often show static cling.The shock that
you sometimes receive after you walk across a rug
touch a doorknob is another example of matters
electrical nature.What causes these phenomena?

• Static cling is best seen when the humidity is
  low.

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Attraction Repulsion

• The electrical properties of matter can be
  summarized as follows
• What are these positive and negative particles?

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Subatomic Particles

• Every neutral (uncharged) atoms contains an equal
  number of positively charged protons () and
  negatively charged (-) electrons.
• of () protons of (-) electrons
• Positive-Negative attractions between the protons
  in one atoms the electrons in another atom hold
  atoms together in bonds.
• Most atoms also contain neutral particles having
  no charge (0) called neutrons.

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Lewis Dot Structure

• Valence Electrons outermost electrons
• Electron Configuration

Energy Level MAX. of electrons
1st 2
2nd 8
3rd 8
4th 18
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Determining approximate placement of electrons

• Chlorine (atomic _____)
• protons _____ electrons _____

Energy Level MAX. of electrons
1st
2nd
3rd
4th
Outermost energy level _________ of valence
electrons __________
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Lewis Dot Structure
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Practice

• Draw the Lewis Dot Diagrams for the following
  Atoms
• Ca
• Li
• F
• Worksheet Unit 1 B.9 Valence Electrons

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Ions and Ionic Compounds

• Recall Molecules make up one kind of compound.
• Ions make up another kind of compound.
• Ions are electrically charged atoms (or groups of
  atoms).
• Ions are formed when neutral atoms gain or lose
  electrons.

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Ions

• Ions are electrically charged atoms (or groups of
  atoms).
• Ions are formed when neutral atoms gain or lose
  electrons.

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Ions

• Recall What charge do electrons carry?
• Negative
• When atoms gain negative electrons, they form
  negative ions.
• When atoms lose negative electrons, they form
  positive ions.

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Ions

• For example, sodium (Na) is 11 on the Periodic
  Table.
• It has 11 () protons and 11 (-) electrons.
• If it lost 1 (-) electron, it would have 11 ()
  protons and 10 (-) electrons.
• It has one more proton than electrons, so it has
  a charge of -1.
• The symbol for a sodium ion is Na1 or just Na.
  (The 1 is understood.)

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Ions

• For another example, chlorine (Cl) is 17 on the
  Periodic Table.
• It has 17 () protons and 17 (-) electrons.
• If it gained 1 (-) electron, it would have 17 ()
  protons and 18 (-) electrons.
• It has one less proton than electrons, so it has
  a charge of 1.
• The symbol for a chloride ion is Cl1- or just
  Cl-. (The 1 is understood.)

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Do Now (day 7)

• List the number of protons, electrons, and
  neutrons in each ion
• O2-
• H
• F-
• Do any of these atoms have complete valence
  shells?

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Objectives

• SWBAT determine the formulas for ionic compounds
• SWBAT name different ionic compounds

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Ionic Compounds

• Oppositely charged ions connect together to form
  ionic compounds.
• For example, sodium ions (Na) connect to
  chloride ions (Cl-) to make sodium chloride
  (NaCl), or table salt.

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Sodium chloride consists of an equal number of
positive and negative ions arranged in a
3-dimensional network called a crystal.

• A scanning electron micrograph shows the cubic
  structure of NaCl crystals.

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A space-filling model of NaCl provides
information about how the individual sodium ions
chloride ions are arranged within the salt
crystal.

• What else does this model suggest about the
  sodium and chloride ions or sodium chloride?

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If an ionic compound dissolves in water, the
individual ions would separate from each other
and spread out throughout the water.To show
that they were now in an aqueous solution, an
(aq) would be added after the symbols for the
ions. Na(aq) Cl- (aq)
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More about Ions

• Na,
• Cl-
• Na, Cl-, Mg2, O2-, Al3, N3-
• NH4, CO32-, SO42-, PO43-

• Cation positive ion
• Anion negative ion
• Monoatomic ions (or monatomic)
• Polyatomic ions

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Common Ions

• See text p. 40 for a list of common ions.

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Practice

• Find trends on the periodic table
• Worksheet Unit 1 B.9 part 2 Lewis Dot Structures

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Formulas for Ionic Compounds

• 2 Rules for Writing Formulas for Ionic Compounds
• 1. Cation first, then anion
• 2. Correct formula will be neutral, with the
  fewest number of each ion needed to make the
  total electrical charge zero
• No charges are shown in the formula.

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Practice Problems

• NaCl
• One Na1 and one Cl1- cancel each other out.
• 1 -1 0
• CaCl2
• One Ca2 needs two of the Cl1- to cancel it out.
• 2 -1 -1 0

Note Negative monoatomic ions change their
ending to ide. Examples above are sodium
chloride and calcium chloride.
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Formulas Containing Polyatomic Ions

• Formulas for compounds containing polyatomic ions
  follow the same rules
• If a subscript is needed, it follows the entire
  polyatomic ion, which is enclosed in parentheses
• For example, the calcium ion has a 2 charge,
  and the nitrate ion has a -1 charge

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Formulas Containing Polyatomic Ions

• For example, the calcium ion has a 2 charge
  (Ca2), and the nitrate ion has a -1 charge
  (NO31).
• Two nitrate ions are needed to balance out the
  charge on one calcium ion.
• The formula for calcium nitrate is Ca(NO3)2.
• No charges are shown in the formula.
• Polyatomic ions do not change their endings.

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Naming Ionic Compounds

• 1. Name the cation, then the anion
• 2. Have the last few letters changed to ide
  (monoatomic ions only)
• Ex. KF, potassium fluoride
• Ex. Ca(NO3)2, calcium nitrate
• Practice Worksheet Unit 1B.9 B.10 Ion
  supplement

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• Write the formula and name the following ionic
  compounds
• 1. Ca2 Br-
• 2. PO43- Ag
• 3. CO32- NH4
• 4. Al3 NO3-
• What does the word ionic mean?

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Practice

• Worksheet (Unit 1B.9 part 3)
• Study for quiz

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IB.11 WATER TESTING

• day10

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Do Now

• Explain what charge the following items typically
  carry and WHY!
• Lithium
• Chlorine
• Calcium
• Draw the Lewis Dot diagram for Li.
• Draw a picture of a heterogeneous mixture of
  elements X and B.

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Objectives

• 1. SWBAT start to review for the test by going
  over the answers review questions.
• 2. SWBAT read and think critically about the
  Riverwood Fish Kill.
• 3. SWBAT create 2 possible hypothesis about the
  Riverwood fish kill.

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Content below may or may not be necessary
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Pure vs. Clean Water

• In the U.S., we all have access to abundant, low
  cost, clean, but not pure water
• Even if the cost was not prohibitive, it would be
  impossible to have 100 pure water.
• Atmospheric gases (e.g., O2, N2, CO2) will always
  dissolve in the water to some extent.

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HOW DO YOU NARROW DOWN THE DATA TO GET THE ANSWER?

• The cause of the fish kill may be related to
  something suspended in or dissolved in the water.
  What might it be?

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Chemistry at Work

• To learn about careers that require knowledge
  about what you are learning about in class right
  now, read text pp. 48-49, Environmental Cleanup
  Its a Dirty Job But Thats the Point

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• Concerns
• Dissolved oxygen (DO) levels will test
• Microorganisms none present
• Dissolved matter must consider amounts effect
  of temperature on solubility will test
• Suspended particles will test
• Other Information
• No illness water conservation tips more water
  trucked in 3 day crisis expected

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Now what?

• Water experts agree that the fish kill was caused
  by something either dissolved or suspended in the
  Snake River.
• How can you determine the exact cause?
• Knowing properties of water properties of
  substances that may be found in it will help.
• Knowing language of chemistry will help you
  communicate your findings.

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