Transcript Ocean Chem Lab Visualsx

Ocean Chem Lab
Visual Stations
Station 1: Egg Station
Procedure:
• Fill the beaker with 150 mL of tap water
• Carefully place the egg into the water
• Observe what happens
• Take the egg out of the beaker
• Weigh 20 grams of salt using the triple beam balance and filter paper
• Add the salt to the beaker and stir with the stirring rod until the salt has dissolved
• Carefully place the egg into the salt water solution and observe what happens.
• CLEAN UP THE STATION BY POURING THE SALT SOLUTION OUT AND RINSING
THE BEAKER. BE CAREFUL NOT TO CRACK THE EGG.
Station 2: Hydrometer Station
Bar graph is used to answer questions 13 to 16
Station 3: Food Coloring Station
Procedure:
• Fill one beaker ¾ full with the clear water labeled “Fresh Water”
• Fill the eye dropper with the red water from the beaker (this is seawater)
• Submerge the red filled eye dropper about half way into the clear water beaker of freshwater
• Slowly release several drops of the red seawater into the clear water beaker
• Observe what happens
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Fill the second beaker ¾ full with the clear water labeled “Seawater”
Fill the eye dropper with the blue water from the beaker (this is freshwater)
Submerge the blue filled eye dropper about half way into the clear water beaker of seawater
Slowly release several drops of the blue freshwater into the clear water beaker
Observe what happens
CLEAN UP THE AREA BY RETURNING THE DROPPERS & DUMPING AND RINSING YOUR 2 BEAKERS
Station 4: Dead Sea
Why is it called the Dead Sea?
Sounds kinda creepy, doesn't it? The name 'Dead Sea' is actually a kinder, gentler translation from the Hebrew name 'Yam ha Maved', which means, 'Killer Sea'. It is some of the saltiest
water anywhere in the world, almost six times as salty as the ocean! The Dead Sea is completely landlocked and it gets saltier with increasing depth. The surface, fed by the River Jordan, is
the least saline. Down to about 130 feet (40 meters), the seawater comprises about 300 grams of salt per kilogram of seawater. That's about ten times the salinity of the oceans. Below 300
feet, though, the sea has 332 grams of salt per kilogram of seawater and is saturated. Salt precipitates out and piles up on the bottom of the sea.
There are no fish or any kind of swimming, squirming creatures living in or near the water. There are, however, several types of bacteria and one type of algae that have adapted to harsh life
in the waters of the Dead Sea. What you'll see on the shores of the Sea is white, crystals of salt covering EVERYTHING. And this is no ordinary table salt, either. The salts found in the Dead
Sea are mineral salts, just like you find in the oceans of the world, only in extreme concentrations. The water in the Dead Sea is deadly to living things. Fish accidentally swimming into the
waters from one of the several freshwater streams that feed the Sea are killed instantly, their bodies quickly coated with a preserving layer of salt crystals and then tossed onto shore by the
wind and waves. Brutal!
The guy to the left is actually floating in the Dead Sea. "But, hey, I thought you said the Dead Sea was DEADLY!" Not to us. Humans are remarkably adaptable. We can swim in the Dead
Sea, just like we can swim in the ocean. Well, people don't really "swim" in the Dead Sea - they just "hang out". That's what's so cool about the Dead Sea. Because of the extremely high
concentration of dissolved mineral salts in the water its density is way more than that of plain old fresh water. What this means is our bodies are more buoyant in the Dead Sea - so you bob
like a cork. In fact, people are so buoyant in this water, it makes it kinda tough to actually swim. Most people like to just kick back in the water and read. It almost looks as though this guy is
sitting on an air mattress that has sunk below the surface, but he's not. He's really just floating, without having to hold is feet in that position! If you think this is easy, try floating like this in a
freshwater swimming pool.
What Caused the Dead Sea to Form?
This lesson takes us back to the subject of plate tectonics. In this part of the world there is a rift forming where two crustal plates are spreading apart. The East Rift Valley runs through most
of Africa, but it starts north of the Dead Sea and runs south along the eastern side of the continent. The Sea is located right along the Rift Valley where the earth's crust is being stretched
thin. To get an idea of how this "crustal spreading" thing works, take a bar of taffy, or taffy-like candy and try to pull it apart. You'll see where the candy starts to come apart it gets really thin
just before it breaks. That's what is happening to the earth's crust in the Rift Valley. Where the earth's crust gets thin that part of the surface sinks downward. Look at the picture at left to see
how the rift forms, sinking downward where the crust is stretched thin. You know what? The Dead Sea is still sinking lower, even today. Scientists figure that the Dead Sea lowers by as
much as 13 inches per year. On a geologic time scale that's incredibly fast!
Why is the Dead Sea so Salty?
We talked about how the surface of the Sea got down so low in elevation, but why is it so salty? All roads lead to the Sea when it comes to the rivers in the area. The Dead Sea is continually
fed water from the rivers and streams coming down off the mountains that surround it. But the kicker is this....no rivers drain out of the Dead Sea. The only way water gets out of the Sea is
through evaporation. And boy does it evaporate! This part of the world get plenty hot. When the water evaporates, it leaves behind all the dissolved minerals in the Sea, just making it saltier.
In fact, it's through the dual action of; 1) continuing evaporation and 2) minerals salts carried into the Sea from the local rivers, that makes the Sea so salty. The fact that the water doesn't
escape the Sea just traps the salts within its shores. There's nothing living in the Dead Sea because it got so salty, so quickly, that evolution has not had a chance to produce any creatures
that could adapt to such brutal conditions.
Station 5
Station 5
Station 6
Both salinity and temperature affect the density of seawater.
A liter of seawater has a higher mass than a liter of freshwater due to the
added mass of the dissolved salts. As density measures mass per unit
volume, saltwater has a higher density than freshwater. Increasing the
amount of salt dissolved in water increases the water’s density.
Temperature affects the density of seawater by changing the volume of
the water itself. Higher temperatures actually cause water to expand,
increasing the amount of space it takes up. The mass of warmer water is
spread over a larger volume than a similar amount of cooler water, so the
warmer water has a lower density. Increasing the temperature of water
results in a decrease in the water’s density.
This graph allows you to estimate the density of any mass of seawater
based on its salinity and temperature. To estimate density, find the point
where the temperature and salinity values for the water intersect. The
blue line on the graph nearest the point of intersection indicates the
density of the water.
Mixing in the oceans depends on the densities of water masses. When
water masses of differing density meet, the mass with the higher density
will sink to the bottom and the mass with the lower density will float on
top of it.