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Rebecca Hansen
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From the name we can tell this takes place in the North Atlantic Ocean
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Both the
temperature and the salinity affect the density of the sea water
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Therefore, when
there is a difference of density between two part of water, the heavy water will sink and the light
water will rise
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The Gulf is placed at the equator, the sun
heats the water and therefore it evaporates
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When the hot water reaches the Northern Atlantic, it cools down
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The salt doesn’t freeze with the water, so the salinity increases
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Down welling is where the heavy water sink to the bottom and replaces the old water whereas a
circulation occurs
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Rebecca Hansen
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There’s a lot
of ice and snow in the north Atlantic, and therefore
most of the heat from the sun is reflected back into
space
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As the sea water absorbs the
heat from the sun, it melts the ice around it
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1
As there is now more water the salinity will drop
which will lower the density
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With higher density the water will not sink as low, as it does now which will most likely slow the
circulation2
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The Global Ocean Conveyer Belt is driven by differences in densities caused by temperature and
salinity
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If there is no difference in density and no circulation, the water will stay still
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Experiment 1 – Control
We put the same amount of water in to two plexiglas chambers
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We added red dye
to one part of the water, so we could identify the water afterwards
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As there is no circulation, it’s not going to
mix
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This can be seen in the picture
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2

http://www
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uoguelph
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htm
http://scied
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edu/longcontent/melting-arctic-sea-ice-and-ocean-circulation

Rebecca Hansen
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Both
parts of water had the same temperature
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Observations:
When we moved the divider, the two part
didn’t mix this time either
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For a minute or so,
the water made wavy-like movements, as can be seen on the picture above
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The water has now formed a halocline
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It’s called halocline, because it’s the salt causing this phenomenon
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Experiment 3 - Circulation caused by temperature and the formation of a thermocline
This experiment is very similar to experiment 2, except this time we use difference in temperature
instead of salinity
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Observations:
When we moved the divider, the same thing
happened as in last experiment
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As this happened, a thermocline formed
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Experiment 4 – local warming and heating
Now we will try to create a circulation, by using
the knowledge of density
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To be able to see the movement in the
water, we put blue dye in the water around the
ice and red dye around the heater
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i
The blue dye sank to the bottom and the red dye floated on top
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The ice and the heater kept changing the temperature of the water around it, which caused a
circulation to form
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The increasing of density essential to the North Atlantic Pump
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When this happens, down welling
occurs
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The whole
circulation depends on increase and decrease of density to keep going
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Global warming could potentially have big impact on humans
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At the moment the ocean
current carry warmth from the tropics, which is afterwards lost in the atmosphere
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If the Global Conveyer Belt were to stop completely, we would see a huge decrease in
temperature in Northern Europe
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Even if the Conveyer Belt only slows
down, it could still lead to cooling in Northern Europe3
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This I
happening at the Mexican Gulf
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As the water evaporates from the sea, the salinity will increase
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Because the salinity
is so high, the density will increase more than decrease
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Experiment:
First we wanted to prove that salt mostly stays in the water, when part of the salty water freezes
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We expected the top to freeze first,
because it was disposed, and therefore we expect the top part to have a lower salinity than the
bottom part
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3

http://scied
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edu/longcontent/melting-arctic-sea-ice-and-ocean-circulation

Rebecca Hansen
1
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We used five
different solutions with known salinity,
and found the conductivity of each
solution
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Ohms law reads: V = R * I
V is voltage, I is current and R is
resistance
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We want to know how well our solution can conduct electricity, so we rewrote the law into:
I = V * G
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These are our results from our five solutions
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We calculated the salinity by dividing the amount of salt with the amount of water
and multiplied it with 100 to get the result in percent
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The reason there is a slight conductivity with no salinity, is because even though the water has a
ph level of 7, there’s still a few HO- and H+ ions in the fresh water
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Rebecca Hansen
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8358x – 0
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To find the salinity of our two parts of
the sea water sample, we need to find the conductivity
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We used the same method as before to
find the conductivity of the two parts
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Now we used the equation to find
the salinity of the two parts
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Top: 7
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25 – 0
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86215
Bottom: 7
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55555556 – 0
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25642222
Conclusion:
With our results we can confirm, that the salt stays in the liquid part, when some of the ice starts
melting
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This is very relevant when talking about the Northern Atlantic Circulation Pump
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The water is already very salty
due to evaporation in the Gulf
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Due to the high density, the water will sink and down welling will occur
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This is the way the Northern Atlantic
Circulation Pump contributes to the Global Conveyer Belt
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There’s a lot of salt dissolved into sea water, most of it is sodium chloride
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NaCl is white crystals in room temperature
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The amount of NaCl in water is
called salinity when measured in percentage
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We used four different methods to determent the salinity in sea water; density measurements,
evaporation, precipitate and titration
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We used the formula: d=m/V where m
is the mass of the sea water in grams and V is the volume measured in cm 3 therefore we use the
unit g/cm3 for density
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i
By finding the density of several solutions with known salinity, we can find the salt content of
the sea water
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We repeated this three times to get
correct and useful answers
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Results:
The mass of the Erlenmeyer flask was 52
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30g
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11g By
dividing the mass and the volume, which is 25 cm3, we get the density
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11/25=1
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0044
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Graph 1
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The graph shows the equation of the line, which is used to calculate the salinity
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131
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0044 – 131
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809964%
Therefore, the salinity of the sea water is 0
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2) Evaporation

Rebecca Hansen
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The boiling
point of water is 100°C and the boiling point of NaCl is 1413°C4
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Procedure:
We heat the sea water sample and wait for the water to evaporate
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Afterwards we heat it for three more minutes and weight it again
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Result:
Mass(flask)

Mass(flask+seawater)

Mass (flask+salt)
Mass (flask+salt)
st heating
After 1
After 2nd heating
86
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90g
87
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66g
As the 1st and 2nd result are so close, we decided to use the 2nd result
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90 with 86
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02g
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66 with 86
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78g
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We divide the mass of the
salt with the mass of the seawater and multiplied with 100 to get the answer in percent
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02/0
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5911827%
By evaporating the salinity shows to be 1
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This
occurs because the two salts mix and make new salts
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By mixing silver nitrate and sodium chloride this reaction occurs:
NaCl (aq) + AgNo3 (aq) -> NaNo3 (aq) + AgCl (s)
Procedure:
We added AgNO3 into the sea water sample
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We
filtered the precipitate and left it to dry
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15g
1
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1
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15=0
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4https://en
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org/wiki/Sodium_chloride

Rebecca Hansen
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Shows relationship between salinity and precipitate
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4
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31 – 0
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266479%
This means by using the precipitate method, the salinity should be 1
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4) Titration
Titration in used to determine the amount of a given compound in a solution
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Procedure:
We added an indicator (K2CrO4) to the sea water sample
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Results:
When we started our experiment, we “zero’ed” the burette, therefore we could read the amount
of AgNO3 used
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3 cm3
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Rebecca Hansen
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Shows relationship between removal of salt (NaCl) using AgNO 3
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We put in the amount of silver nitrite used as x, which means y will be the salinity
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1169 * 15
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0019 = 1
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78667
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809964

Evaporation
1
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266479

Titration
1
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While the other three are rather similar there is still a difference of approximately 0
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There’s different weaknesses for all of the methods
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The scale we
used could only weight up to two decimals, which makes it less precise
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Both the temperature and the salinity has an impact, and we did not check the
temperature for any of the solutions
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We might not have evaporated all water either
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Then you use precipitation, there is always a chance of dropping some
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This may be why the result is lower than evaporation and
titration
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Filling the burette correctly is essential, as there mustn’t be any
air bubbles left
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Rebecca Hansen
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The ESS part explains how density works
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Chemistry shows
how to calculate the salinity, which is an important factor when measuring density
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ESS and physics help explain down welling which is how the Pump works
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You
research your questions and find information which you build a
hypothesis out of
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You repeat, and if the results are the same, you can
either confirm or not confirm the hypothesis
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We had a
hypothesis and afterwards tested it out
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In both physics and chemistry, we use quantitive results
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In ESS we use
qualitative result, where we observe what’s happening, and
explain further from our observations
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We had the hypothesis that when sea water freezes, it
leaves behind most of the salt
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We drew a
conclusion that the hypothesis was right

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