Collaboration Teams
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) From the save dropdown menu choose "save with comment , place a summary of what you did and sign it (e.g. "I answered chp 26 question 3" - Tom S.) Then click Save.


1. Why is water considered a polar molecule Smiley-02-june.gif
Water is considered a polar molecule because of its shape. (like Micky Mouse) The covalent bond between the two hydrogen atoms and the oxygen atom allow them to share a pair of electrons. There are 4 electrons in the oxygen atom that are not involved in the bond, causing the oxygen to be negatively charged. Therefore, the hydrogens are positively charged, making water polar.
-Ashley A.

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.Smiley-02-june.gif

a. Cohesion - Cohesion is when only hydrogen bonds hold a certain substance together. Water molecules contain oxygen and hydrogen atoms. When these H20 molecules come in close contact with one another, hydrogen bonds form, and hold certain substances together. This allows cohesion to occur very easily. Cohesion also contributes to the transport of water and dissolved nutrients against gravity in plants.

b. Adhesion - The definition of adhesion is when one substance clings to another substance. The adhesion of water to the walls of the cells helps counter the downward pull of gravity. This allows cells to get water to the rest of their bodies instead of just one part of their bodies.

c. Surface tension - Surface tension is related to cohesion. It is the measure of how difficult it is to stretch or break the surface of a liquid. Water has a higher surface tension than most other liquids. Water molecules are bonded together on the surface of the liquid, which has a certain force that can be broken. Certain animals can stand, walk, or run on the surface of water without breaking it, due to the hydrogen bonds being in close contact with one another.


d. High specific heat - The specific heat of a substance is defined as the amount of heat that must be absorbed or lost for 1 gram of that substance to change its temperature by 1 degree Celsius. One of the water molecules extraordinary characteristics is it to have a high specific heat temperature. Water has 1 cal/g/degree Celsius, compared to other molecules, like ethyl alcohol, which has 0.6 cal/g/degree Celsius. On Earth, water's high specific heat has an effect on life. The ocean can absorb heat during the daytime and only warm up a couple of degrees. It also stabilizes the ocean's temperature to keep marine life alive and in a good environment.

e. Heat of vaporization - Heat of vaporization is the quantity of heat a liquid must absorb for 1 gram of it to be converted from the liquid to the gaseous state. Water also has a high temperature for the heat of vaporization. The hydrogen bonds that hold water together must be broken before any of the other molecules can be extracted from the liquid. The high temperature for heat of vaporization helps Earth's climate and controls how much water is evaporated and condensed everyday.

f. Evaporative cooling - As a liquid evaporates, the surface of the liquid that remains behind cools down. This is called evaporative cooling. The molecules with the higher kinetic energy leave the gas first. This leaves the 'cooler' molecules behind to keep the water at a consistent temperature. This cooling process contributes to the stability of temperatures in any body of water. It eliminates the threat of the water overheating and harming any organisms that live underneath it.

- Chris A.
(Purple Team)

3. What is special about water and density Smiley-02-june.gif
Ice floats on liquid water, which means it is less dense as a solid. While other materials contract when they solidify, water expends. Hydrogen bonding allows water to expend when it solidifies.
- Alina D.

external image wq-iceberg-underwater.jpg
-Mike G.

-Dahlia M.

4. Define the following terms and provide exemplary pictures or video
a. Solute- the substance that is dissolved in a solution

b. Solven- is the dissolving agent in a solution
c. Aqueous solution
is when the water is a solvent in a solution

d. Hydrophilic
any substance, whether ionic or polar, that has an affinity for water (loves water).

e. Hydrophobic
substances that are nonionic or polar, repel water, and do not have a
affinity to it, in other words fears water


f. Colloid
a stable suspension of fine particles in a liquid

g. Hydration shell
the sphere of water molecules around each dissolved ion

h. Molarity
the number of moles of solute per liter of solution

molarity.gif molarity0.gif

-Alecia Seliga

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

-Alecia Seliga

6. What defines an acid and a base - (examples) Smiley-02-june.gif
An acid is often used by biologists. It is a substance that increases the hydrogen ion concentration of a solution. An example would be when hydrocholoric acid is added to water, the hydrogen ions no longer associate with the chloride ions. A base would be the substance that lowers the hydrogen ion concentration of a solution.

  • 7. Why are “apparently” small changes in pH so important in biology -examples

small changes in pH are important because when the pH changes slightly the actual concentrations of the H+ and OH- change substantially like temperature, it can make enzymes and the active sites inactive

"Apparently" small pH levels are measured logarithmically, so a change of 2 in pH actually means that it varies by a factor 1000. Ph determines many of the organisms that can survive in certain areas. Certain animals cannot survive in etremely acidic or extremely basic conditions.

8. What is a buffer and explain the carbonic acid buffer system in human blood Smiley-02-june.gif
Buffers are solutions which resist change in pH upon small addition of acids or bases. The main job of the carbonic acid system is to regulate the body’s pH. The lungs eject CO2 which raises the pH. Hydrogen ions have to be consumed with bicarbonate ions in order to produce CO2. To prevent from the loss of too much hydrogen’s, bicarbonate ions are removed. As a result, the equilibrium is shifted and more hydrogen ions are produced which in conclusion, lowers the pH.

9. What is acid precipitation and why is it important to living organism

  • Precipitation that is lower or more then pH of 5.6 can damage the environment by contaminating lakes and streams and other water sources. It is caused by pollutants in the atmosphere mixed with the water in the air. The acid percipitation that falls on land washes away certain mineral ions, such as calcium and magnesim ions that are needed to buffer the soil solution and are essential nutrients for plant growth.
  • acid-rain-1a.jpg