Chemistry II:

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Biology Partnership (A Teacher Quality Grant)

• Chemistry II
• Properties of Water and pH
• Nancy Dow
• Kathrine Alexander

Gulf Coast State College Panhandle Area Educational Consortium
5230 West Highway 98 753 West Boulevard
Panama City, Florida 32401 Chipley, Florida 32428
850-769-1551 877-873-7232
www.gulfcoast.edu
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Pre-test

• Breaks
• Q A boards
• Asking questions
• Our approach to the standards to this lesson

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Florida Next Generation Sunshine State Standards

• SC.912.L.18.12 Discuss the special properties of
  water that contribute to Earths suitability as
  an environment for life cohesive behavior,
  ability to moderate temperature, expansion upon
  freezing, and versatility as a solvent.
  (Moderate)
• Benchmark Clarifications
• Students will explain the properties of water at
  a conceptual level.
• Students will explain how the properties make
  water essential for life on Earth.
• Content Limits
• Items referring to the properties of water are
  limited to hydrogen bonding, polarity, cohesive
  behavior, ability to moderate temperature,
  expansion upon freezing, and versatility as a
  solvent.
• Items may address adhesion but will not assess
  adhesion

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Bell ringer

• Time Warp water droplets

• Time Warp water droplets

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(No Transcript)
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THE PROPERTIES OF WATER Water has some very
unique properties that make this molecule unlike
ANY other. And we are made up of about 70 water!
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Your body is made up of mostly of water.
Approximately 85 of your brain, 80 of your
blood and 70 of your muscle is water. Every cell
in your body needs water to live.
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Unique properties of Water
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Cover page

• Write the book title - PROPERTIES OF WATER
• Sketch and color a water molecule
• In the Upper right corner, write your name

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PAGE ONE (front side)

• Write the Page title, POLARITY, centered at the
  top of the page.
• Draw and color (Oxygen-RED and Hydrogen- BLUE)
  water molecules held together by hydrogen bonds
• Write, bullet, and answer these
• questions
• What is meant by polarity?
• Which end of the water molecule attracts most of
  the electrons and acts negative?
• Which end acts positive?
• How do water molecules act like little magnets?

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Water is a Polar Covalent molecule- (charges
at opposite sides of molecule) POLAR means an
unequal distribution of the charge.
H2O
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HYDROGEN BOND BETWEEN WATER MOLECULES
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A Drop in the Ocean Lab
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• Weve heard that wax or oils repel water. But
  that isnt true. Water is so attracted to other
  water molecules that anything between them is
  squeezed out of the way.

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States of Water

• Only substance to that exists free in nature in
  all three states

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PROPERTIES OF WATER

• WATER IS THE UNIVERSAL SOLVENT---It dissolves
  other polar molecules a molecule that can
  attract a water molecule. Like dissolves like
  polar dissolves polar
• WATER MOLECULES ARE COHESIVE AND
  ADHESIVE---Transport of water in organisms
  example Trees
• Cohesion- a property of like molecules sticking
  together (water attracted to other water
  molecules
• Adhesion- the tendency of dissimilar particles to
  cling to one another  
• WATER HAS A HIGH SURFACE TENSION----Water bugs
  walk on the surface of water
• FROZEN WATER (ICE) IS LESS DENSE THAN LIQUID
  WATER SO IT FLOATS---Keeps organisms alive in the
  bottom of a frozen lake
• WATER HAS THE ABILTIY TO MODERATE TEMPERATURE
  water temperature effects coastal communities
  temperature

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PAGE ONE (Backside)

• Write the Page title, UNIVERSAL SOLVENT, centered
  at the top of the page.
• Draw and color a solution
• including solvent and a solute
• Write, bullet, and answer these questions
• What is a solvent?
• Why is water called a universal solvent?
• What is a solute?
• Which type of molecules, polar or nonpolar,
  dissolves in water?
• Are materials that dissolve in water hydrophobic
  or hydrophilic?

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Universal Solvent

• Since unlike charges attract, the negative end
  of water will be attracted to the positive sodium
  ion. The positive end of water will be attracted
  to the negative chloride ion.Since water is
  always in motion, it will pull on the ionic
  compound and move the ions away from each other.
  This dissolves the ionic compound.

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Many compounds dissolve in water.

• A solution is formed when one substance dissolves
  in another.
• A solution is a homogeneous
• mixture.
• Solvents dissolve other
• substances.
• Solutes dissolve in a solvent.

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• Like dissolves like.

• Polar solvents dissolve polar solutes.
• Nonpolar solvents dissolve nonpolar solutes.
• Polar substances and
• nonpolar substances generally remain separate.

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Common Misconceptions

• Students often thinks that all solutes are solids
  and all solvent as are liquids.
• Correcting the misconception
• Solutions can involve different states of matter

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PAGE TWO (Front side)

• Write the Page title, COHESION, centered at the
  top of the page.
• Sketch and color the water droplet
• Write, bullet, and answer these questions
• What is cohesion?
• Cohesion produces _____________ tension as the
  water molecules hold tightly together.
• How do living things like insects use surface
  tension?

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PAGE TWO (Backside)

• Write the Page title, ADHESION, centered at the
  top of the page.
• Sketch and color the picture below.
• Adhesion pulls the liquid up the sides of the
  straw (capillarity).
• Write, bullet, and answer these questions
• Define adhesion.
• Adhesion produces an effect called ______________
  action when you place a straw in a liquid
• Explain how adhesion and cohesion help plants
  move materials.

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• Hydrogen bonds are responsible for three
  important properties of water.

• Cohesion - water molecules stick to each other
• Adhesion - water molecules stick to other
  substances

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Cohesion

• Waters tendency to cling together
• Water in space

When the negative end of a water molecule
attracts the positive end of another water
molecule, and the molecules stick together, this
is called cohesion.
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How water stacks up
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15 minutes!!
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Adhesion

• Adhesion, or capillary action, is when water
  molecules are attracted to other substances with
  a negative or positive charges. This is why water
  "climbs" up a piece of paper or a straw above the
  surface level of the water.        
•  
• This figure shows water adhesion

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Because of the cohesive properties of water,
trees such as the giant sequoia are able to
transport water molecules from the soil to their
leaves 300 ft. above.
WATER STRONG COHESIVENESS
300 ft.
Water molecule released into the atmosphere
As each water molecule evaporates, it pulls
additional water up through the tree because of
the sticky-ness of the hydrogen bonds that link
the water molecules.
Water molecules pulled upward
6-ft.-tall man
Water molecule pulled into root system
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Phloem and Xylem
-Phloem-Transport sugars and molecules created by
the plant. Transports food made during
photosynthesis.Xylem-System of tubes in a plant
that transport water and dissolved minerals. The
xylem distributes the water throughout the plant.
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Surface Tension

• The cohesive forces between liquid molecules are
  responsible for the phenomenon known as surface
  tension.
• The molecules at the surface do not have other
  like molecules on all sides of them and
  consequently they cohere more strongly to those
  directly associated with them on the surface.
• This forms a surface "film"  that allows insects
  to walk on water

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WATER HIGH SURFACE TENSION
Pressure applied to water surface
Hydrogen bond
V-shaped water molecules are held together by
hydrogen bonds. The bonds are just strong enough
to give water a surface tension with net-like
properties.

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Trouble on the Surface Lab
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LAST PAGE (Inside of back cover)

• Write the Page title, INSULATION, centered at the
  top of the page.
• Sketch and color the ice crystal.
• Write, bullet, and answer these questions
• When is water the densest?
• Explain why ice floats?
• How is a lake or river that freezes over helpful
  to the organisms in the water?

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WATER LOWER DENSITY WHEN FROZEN
Water is densest at 4C
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Expansion of water contributes to the fitness of
the environment for life

• Prevents deep bodies of water from freezing solid
  from the bottom up.
• Since ice is less dense, it forms on the surface
  first. As water freezes it releases heat to the
  water below and insulates it.
• Makes the transitions between seasons less
  abrupt. As water freezes, hydrogen bonds form
  releasing heat. As ice melts, hydrogen bonds
  break absorbing heat.

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Thermal Expansion
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WATER HIGH HEAT CAPACITY
4 Molecules that make up sand, on the other hand,
dont have so many hydrogen bonds, so the heat of
the sun just increases the temperature.
1 Heat (energy) from the sun disrupts some of the
hydrogen bonds between water molecules.
2 New hydrogen bonds are formed almost as quickly
as they are disrupted.
3 Because heat energy from the sun is used up
breaking and re-forming hydrogen bonds, the water
temperature doesnt increase by much.
Disrupted bond
Newly formed bond
Sun

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Other unique properties of water

• High boiling point - 100 oC
• Low freezing point- 0 oC
• Viscosity increases as its temperature is lowered
• A relatively high density to support animals with
  no or delicate skeletal systems
• Latent heat of evaporation highest of all
  substances
• Latent heat of fusion- highest except ammonia
• Transparency relatively great

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Why is water so important to living organisms?

• Water acts as a solvent to provide a liquid
• environment for biochemical reactions.
• Water is also a transporter of nutrients, waste
  products, blood, and materials within cell
• Water dissolves polar compounds and does not
  dissolve nonpolar compounds. This is important
  for both biochemical reactions and crucial
  hydrophilic/hydrophobic interactions in protein
  folding. 
• Water is an important reactant in certain
  biochemical reactions such as electrolysis
  reactions and the first step of the
  photosynthetic electron transport chain.
• Water has a high specific heat capacity to
  facilitate better maintenance of internal
  temperature and the usage of evaporation to cool
  down.

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Follow up

• Q/A Board
• Problem solving issues in class
• Additional activities
• Properties of Water Lab H.O.T.
• Water Tutorial
• Wonder of Water 6.5 Cloze

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Florida Next Generation Sunshine State Standards

• SC.912.P.8.11 Relate acidity and basicity to
  hydronium ion and hydroxyl concentration and pH.
• No specific Biology standard for pH but need to
  understand because it is referred to in the
  enzymes standard as well as in reference to
  aquatic systems

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Bell Ringer

• Acid Bases and pH- flipped classroom
• Acid and base rap
• Acid and base Music video

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Acids and bases

• The pH is a measure of how acidic or basic a
  solution is.

• A scale with values ranging from below 0 to
  above 14 is used to measure pH.

More basic
More acidic
Neutral
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Acids and bases

• Substances with a pH below 7 are acidic. An acid
  is any substance that forms hydrogen ions (H)
  in water.

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• A neutral solution has a pH of 7.

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Acids and bases

• Substances with a pH above 7 are basic.
• A base is any substance that forms hydroxide ions
  (OH-) in water.

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• It is a logarithmic scale, based on powers of 10,
  so that 1 pH unit change equals a 10 fold change
  in H ion concentration! A pH of 6 is ten times
  more acidic than a pH of 7.

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pH scale is logarithmic using powers of ten
THE pH SCALE
H ion
Water
OH ion
ACIDS
BASES
Bases are fluids that have a greater
proportion of OH ions to H ions. OH ions
bind with H ions, neutralizing acids. Strong
bases are caustic to your skin. Bases can be
found in many household cleaners. Bases are
generally bitter in taste and soapy.
Acids are fluids that have a greater proportion
of H ions to OH ions. H ions are very
reactive. Strong acids are corrosive to
metals. Acids break down food in your digestive
tract. Acids are generally sour in taste.
Free H
Free OH-
0
7
14
13
12
11
10
9
8
6
5
4
3
2
1
Water
Bleach
Battery acid
Beer
Baking soda
Ammonia
Coffee
Soda
Blood
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pH SCALE
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ACIDS AND BASESAcidsFree
HydrogensBasesFree Hydroxides
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pH value times acidity or alkalinity exceeds that of pure water (7.0)
Acidic 0 10,000,000
1 1,000,000
2 100,000
3 10,000
4 1,000
5 100
6 10
Neutral 7 1
8 10
9 100
10 1,000
11 10,000
12 100,000
13 1,000,000
Alkaline 14 10,000,000
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How does pH affect life?
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How does pH affect enzymes?

• A change in pH disrupts an enzyme's shape and
  structure.
• In general enzyme have a pH optimum.
• However the optimum is not the same
• for each enzyme.
• Different enzymes might have very different pH
  optima

• Green- enzyme pepsin which degrades
• proteins (protease) in the stomach
• Red- enzyme carbonic anhydrase that works in
• the neutral pH of your cytosol.

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Buffers A Mechanism to prevent pH changesto
keep the pH within normal limits because they
take up excess hydrogen ions (Examples Tums or
Rolaids are buffers for stomach acidity).--- Our
body has buffer systems (Homeostatic
mechanisms)---Example Buffers to keep our blood
pH at 7.3 - 7.4
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Acid Base Lab
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Cabbage juice indicator
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Follow up

• Q/A Board
• Problem solving issues in class
• Additional activities
• pH Factor -interactive
• Interactive pH scale

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Post Test