Collaboration Teams - Members share responsibility for posting refined answers to the guided readings - succinct, relevant, clear, and with pictures or a video to compliment.
When contributing to the reading guide, follow these steps:
1) First complete the reading guide on your own from the chemistry unit page.

2) Write your response to a question in word and then copy it. Be sure to upload pictures and/or video for each question.
3) Click on the edit button and then go to the appropriate question and paste your answer below it. Sign your contribution with your first name and last initial and TEAM COLOR
4)
Scroll to the very bottom and in the Optional comment box, place a summary of what you did and sign it (e.g. "I answered chp 26 question 3" - Tom S.) Th en click Save.

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Shayne
Laura
Steven
Martin
Corrine
Emily
Kim
Jordan
Jared
Mario
Alyssa
Zach
Brian
Sean
Jackie
Sawyer
Dan
Keely
Illian
Jim
Amanda
Adam

Steph
1,3
2
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9


1. Why is water considered a polar molecule?
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charge difference results from oxygen acting as an electron "hog"

Water is considered a polar molecule because its opposite ends are different charges. This is due to the fact that it is a “V” shaped molecule, pushing opposite charges away from each other.
external image water.JPG
Steve W.

2. For each of the below listed properties of water – briefly define the property and then explain how water’s polar nature and polar covalent bonds contribute to the water special property. Include an example in nature (PICTURE) of each property also.
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Excellent!


a. Cohesion
: the bonding together of like molecules. In liquid form, hydrogen bonds are very fragile, causing them to form, break, and re-form with great frequency. At any instant, all of the water molecules are bonded to their neighbors, holding the substance together. Cohesion from hydrogen bonding contributes to the transport of water and dissolved nutrients against gravity in plants. The H bond causes an upward pull that transmits water from the roots of the plant to the leaves during evaporation.


cohesion.gif


b. Adhesion:
the attraction between different kinds of molecules. Water has the ability to cling itself to other substances due to its polarity. This helps water stick to cell walls in plants and counter the downward pull of gravity.

adhesion.jpg


c. Surface tension
:
a measure of how difficult it is to stretch or break the surface of a liquid. Between the water and the air exists hydrogen-bonded to one another and to water below, making the water seem like it is coated with an invisible film. This can be observed by slightly overfilling a drinking glass; the water will stand above the rim without spilling.

meniscus-on-water-surface-tension-supporting-steel-paperclip-in-drinking-glass-tumbler-beaker-8-AJHD.jpg


d. High specific heat
: the amount of heat that must be absorbed or lost for 1 g of a substance to change its temperature by 1 degree Celsius. The specific heat of water is 1 calorie per gram per degree Celsius; therefore water has the ability to stabilize its own temperature. It can also resist changing its temperature when it absorbs or releases heat. Heat must be absorbed to break hydrogen bonds and heat is released when hydrogen bonds form.

Large bodies of water on Earth absorb and store huge amount of heat from the sun during the daytime and summer. At night and during winter, the gradually cooling water can warm the area causing milder climates in coastal regions. Living organisms are also more able to resist changes in their own temperature because they are made of primarily water.


e. Heat of vaporization
: the quantity of heat a liquid must absorb for 1 g of it to be converted from the liquid to the gaseous state. Water requires a high level of heat to evaporate because its hydrogen bonds must be broken before the molecules can be released from the liquid. This helps moderate Earth’s climate because a considerable amount of solar hear absorbed by tropical seas is consumed during the evaporation of surface water. As the moist air circulates poleward, heat is released and condenses to form rain.

capillary.jpg

f. Evaporative cooling
: the property of a liquid whereby the surface becomes cooler during evaporation, owing to a loss of highly kinetic molecules to the gaseous state. This contributes to the stability of temperature in lakes and ponds and prevents terrestrial organisms from overheating. An example would be evaporating of sweat from human skin, which dissipates body heat and helps prevent overheating on a hot day.
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Water Movie



Purple Team

3. What is special about water and density? Smiley-02-june.gif
Water is less dense as a solid than as a liquid. It expands when it solidifies, instead of contracting like most other substances.

external image ice-water-volume.jpg

Steve W.



4. Define the following terms and provide exemplary pictures or videos:
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can you more clearly relate examples to definitions?

a. Solute
The substnce that is dissolved. If water and sugar were mixed, sugar would be the solute.
b. Solvent
this picture illustrates, hydrophillic atoms Na and Cl.  They are clearly so because either the possitive or negative ends of polar water are attracted to the ion.  Around the ion is the hydration shell or cloud of attracted water molecules.
this picture illustrates, hydrophillic atoms Na and Cl. They are clearly so because either the possitive or negative ends of polar water are attracted to the ion. Around the ion is the hydration shell or cloud of attracted water molecules.

The dissolving agent of a solution. If water and sugar were mixed, water would be the solvent. It dissolves the sugar.
c. Aqueous solution
A solution in which water is the solvent. An aquaeous solution would include water and sugar.
d. Hydrophilic
Having an infinity for water (likes water). Sugar is dissolved in water because it is hydrophilic.
e. Hydrophobic
Having an aversion for water (dislikes water). Oil does not like water and so it does not mix into water.
f. Colloid
A mixture made up of a liquid and particles that remain suspended in that liquid. Oil and water would be an example of a colloid, because it beads up and floats in the water.
g. Hydration shell
The sphere of water molecules around each dissolved ion. The picture of the broken up sodium chloride above shows hydration shells around the ions.
h. Molarity
A common measure of solute concentration, referring to the number of moles of solute per liter of solution.




The water in this picture is the solvent because it will, once enough is added, dissolve the water.  The water is the the solute because it will be dissolved by the water in this aqueous solution.
The water in this picture is the solvent because it will, once enough is added, dissolve the water. The water is the the solute because it will be dissolved by the water in this aqueous solution.


oil forms beads such as these in water because it is hydrophobic and cannot be dissolved by water
oil forms beads such as these in water because it is hydrophobic and cannot be dissolved by water

- Jared and Jordan


5. upload a diagram or video to demonstrate the dissociation of the water molecule and then relate this to pH. Smiley-02-june.gif
dissociation_of_water.jpg


  • When a source of H+ ions is added to a solution, the dissociation reaction is driven to reduce the concentration of OH- ions, so that the value of pH will decrease.
  • When a source of OH- ions is added to a solution, the dissociation reaction is driven to reduce the concentration of H+ ions, so that the value of pH will increase.




    mario and zack pink team


6. What defines an acid and a base - (examples)? Smiley-02-june.gif
  • An acid is a substance that increases the hydrogen ion concentration of a solution. Some examples of acids are battery acid, which is a strong acid, and orange juice which isn’t as strong. A base is any substance that reduces the hydrogen ion concentration of a solution. Some examples of bases are hand soap and bleach.

  • phscale.gif
  • – Jackie, Brian, and Sean à Yellow Team


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7. Why are “apparently” small changes in pH so important in biology -examples? Smiley-02-june.gif
  • ​The pH is measured logarithmically. If pH varies by 2 it actually varies by 1000. pH levels regulate the types of plant and animal species that can live in an area.
  • external image pHchart.gif
  • -Ilian and Sawyer
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8. What is a buffer and explain the carbonic acid buffer system in human blood.
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confusing so I added video

  • Buffers are substances that minimize changes in the concentrations of H+ and OH- in a solution. Carbonic acid buffers regulate the pH level in our blood because carbonic acid can give away H+ if there are too many OH- in the blood but then can take H+ back from the blood if there are too many hydrogen ions in the blood. This minimizes change in pH in your blood.
  • external image 20051103062911%21Acetic_acid_deprotonation.png
  • -Ilian and Saywer





9. What is acid precipitation and why is it important to living organisms? Smiley-02-june.gif

  • Acid precipitation refers to rain, snow, or fog with a pH level lower or more acidic than pH 5.6. It is not beneficial because it can damage life in lakes and streams. It attacks wildlife crops, and water environments. It can be good for an environment because it breaks down certain minerals that both plants and animals need. (Red Team)