Webquest for Water Chemistry
http://www.windows2universe.org/earth/Water/dissolved_salts.html
1. Define Salinity:
Salinity is the salt content dissolved in water.
2. In what units do scientists report salinity? Give an example of what the unit
means.
Salinity is reported in parts per thousand (ppt) or in percentages. If the
average salinity is 1ppt, for every 1 parts or grams of salt there is 1,000
grams of seawater.
3. What is the average salinity of the ocean?
The average salinity of oceanwater is about 35ppt.
4. What % of the ocean is salt?
3.5% of the ocean is salt.
5. List the 6 main dissolved salts in the ocean:
The main dissolved salts in the ocean include chloride, sodium, sulfate,
magnesium, calcium, and potassium.
http://www.windows2universe.org/earth/Water/ocean_chemistry.html
6. What makes the ocean salty?
Rainwater dissolves rocks and minerals releasing salts which runoff into
the ocean from rivers. When the water evaporates from the ocean its
leaves these minerals causing the ocean its saltiness.
7. What greenhouse gas dissolves in ocean water?
Carbon dioxide is a greenhouse gas that dissolves in ocean water.
http://www.windows2universe.org/earth/climate/ocean_acidification.html
8. What does CO2 become when too much of it dissolves in the ocean?
When there is too much CO2 dissolved in the ocean it makes the water
very acidic.
9. What do many marine creatures use to build their shells?
Some marine creatures build their shells from calcium carbonate.
10. What does acid do to marine shells?
Acid dissolves calcium carbonate which makes it harder for marine
creatures to build their shells and skeletons.
http://www.windows2universe.org/earth/Water/density.html
11. What is the average density of ocean water? Is it more or less dense than
fresh water?
The average density of ocean water is about 1027 kg/m^3 and is more
dense than freshwater.
12. What are the 2 main factors that affect the density of sea water?
The main factors that affect density of seawater are the temperature and
the salinity of the water.
13. What happens to the density of the ocean as you go to the bottom of the
ocean?
As you descend further into the ocean the colder it is and the denser the
water there is.
http://www.youtube.com/watch?v=TDEzBWjQpQI&feature=related
14. Why do you think this man is able to float so easily in the dead sea?
The man in the video is able to float because of the high salinity of water
in the dead sea and the buoyancy it provides.
http://www.extremescience.com/dead-sea.htm
15. What percent of the dead sea is salt?
35% of the dead sea is dissolved salts.
16. How much saltier than the ocean is the dead sea?
The dead sea is about 10 times saltier than the ocean.
17. Why do you think only certain types of bacteria can survive in the dead sea?
Why do fish instantly die?
Bacteria is a hardy organism here when life on earth just began in extreme
conditions so it makes sense they can survive here. Fish on the other
hand die instantly because the salt creates to much acidity and they enter
the water so abruptly their bodies are unable to handle the conditions.
18. Why is the dead sea very dense?
The dead sea is very dense because of its high concentration of dissolved
mineral salts.
19. What affect does this density have on people swimming in the dead sea?
Because the density is so high in the dense sea people are able to float
without struggle but this also makes it harder to swim.
http://globetrooper.com/notes/why-cant-we-drink-sea-salt-water/
20. Give 2 reasons why our bodies need water.
Our bodies need water for many reasons, two of them being a way our body
temperature is able to stay in check and also as a way to flush toxins and
other waste from our bodies.
21. How do our bodies cool off if we are hot?
Sweating or water evaporating from our skins cools our bodies down when
we are hot.
22. Under normal conditions, our bodies should be in an
__isotonic________________ state, where the concentrations of water in our
cells equals that of outside of our cells.
23. If the salinity (amount of salt) outside of you cells is greater than the salinity
inside, what will happen?
When the salinity outside is greater than the salinity inside the cells, water
will move from the inside to the outside to help balance the concentration.
24. Why do runners need to drink sports drinks that have sodium and
potassium?
Having enough of these minerals allows muscle cells to retain the right
amount of water.
25. What will happen to your cells to you if you drink salt water?
When a person drinks salt water the salt pulls more water out of your cells
where is will lose its shape and dehydrate you in the process.
26. So if at the aquarium you get stuck on a tiny boat in the salt water tank and
get really thirsty, is it okay to take a quick drink of water to quench your thirst?
It won’t cause much harm, but it will not quench your thirst. Not
recommended.
http://marinebio.org/oceans/ocean-chemistry.asp
Based on the diagram of a water molecule, what do you notice about the polarity
(charges) of the water molecule itself?
The polarity charges of the water molecule include the two hydrogen
atoms which are both positively charged and the oxygen atom which has a
negative charge.
http://dl.clackamas.edu/ch105-05/definiti.htm
What determines the pH value of water? (What are we determining the
concentration of?)
The number of hydrogen atoms in water determines its pH.
http://www.marinebio.net/marinescience/04benthon/dsvents.htm
When did we discover deep sea hydrothermal vents?
We first discovered deep sea hydrothermal vents in 1977.
Why is this date so surprising?
The time of this discovery is surprising as we have been studying the
ocean for a very long time and just discovered this.
Through what process do the bacteria get their “cell food” or energy? How does it
work?
The vent bacteria get their “cell food” through the process of
chemosynthesizing minerals in the water. This process is able to happen
because of the high concentration of dissolved minerals near the vents
that allow bacteria to manufacture their food.
Why is this discovery so amazing?
Before the discovery of hydrothermal vents ecologists believed all
ecosystems needed sunlight so photosynthesis could occur and producers
could become food for consumers. This is unlike the ecosystems that
surround hydrothermal vents where no sunlight is needed for life because
of the minerals provided instead.