OCEN 1010 – Intro to Oceanography
Worksheet 2 - Chemical Oceanography
NAME:
Chemical oceanography is the study of ocean chemistry: the behavior of the chemical elements within the
Earth's oceans. The ocean is unique in that it contains nearly every element in the periodic table (most in very
very small quantities). Chemical oceanographers and marine chemists study the composition of seawater, its
processes and cycles, and the chemical interaction of seawater with the atmosphere and sea floor. Their work
may include analysis of seawater components, the effects of pollutants, and the impacts of chemical processes
on marine organisms. They may also use chemistry to understand how ocean currents move seawater around
the globe and how the ocean affects climate or to identify potentially beneficial ocean resources such as
natural products that can be used as medicines.
Purpose:
To see the effect of salinity and temperature upon the density of water
Materials:
Salt water, fresh water, hot water, cold water, index cards, food coloring, 2 glass containers, plastic container
Problem Question:
What is the effect of temperature and salinity on the density of water?
Hypothesis: Create a hypothesis for this lab (after reading through the lab procedures, and BEFORE starting
the lab).
Discussion:
We know from class and the text book that the density of seawater is governed by both temperature and
salinity. Salinity is the amount of dissolved solids in seawater. It’s usually measured in parts per thousand
0
(ppt or /00). The easiest way to think of salinity is the number of grams of solid dissolved in a kilogram of
seawater. For example, if you had 25 grams of table salt in a bowl, and poured fresh water into the bowl,
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stirring constantly to dissolve the salt until you had 1000 grams of saltwater, you would have 25 /00 salinity,
or 25 ppt. Note that 25 ppt is the same as 2.5%.
In this lab we will look at the effects of both salinity and temperature on density.
Circle the correct word to make a true statement:
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•
Density of water INCREASES / DECREASES as temperature increases.
•
Density of water INCREASES / DECREASES as salinity increases.
Ocen1010v.20170305
Lab #2 – OCE 101 – T/S/ρ Seawater
NAME:
The above TS diagram shows Density (ρ) of water as a function of Salinity (S) and Temperature (T). This
diagram allows you to determine one unknown variable based on the other two known variables.
For example, to determine unknown salinity when you know the temperature and density: Place one
finger on the temperature line. Use another finger to follow the density curve to the temperature line.
Where the two intersect, go straight up or down to read salinity.
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NAME:
Lab #2 – OCE 101 – T/S/ρ Seawater
Using the TS Diagram, fill in the table
(be precise!)
WATER MASS
TEMPERATURE
SALINITY
1
18.0 °C
34.5 ppt
2
10.0 °C
3
1.0265
32.9 ppt
If these three water masses came together, what would happen?
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DENSITY
1.0245
NAME:
Lab #2 – OCE 101 – T/S/ρ Seawater
Using the Global Salinity Diagram, answer the questions
Where do you find the highest areas of salinity?
WHY?
Where do you find the lowest areas of salinity?
WHY?
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Lab #2 – OCE 101 – T/S/ρ Seawater
The Hydrological Cycle
NAME:
Why is the water cycle studied in Oceanography?
Draw a basic water cycle including the following labels:
Evaporation, Transpiration, Condensation, Infiltration, Groundwater,
Runoff, Precipitation.
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Lab #2 – OCE 101 – T/S/ρ Seawater
Interactive Laboratory (completed in class)
NAME:
Follow the procedure to demonstrate the effects of temperature and salinity on the density of water.
BE SURE TO FOLLOW DIRECTIONS.
Procedure:
1. Fill both glass containers with fresh water.
2. Place both containers in the plastic container on your desk.
3. Put ONE drop of yellow food coloring into flask 1.
4. Put ONE drop of green food coloring into flask 2.
5. Put ONE teaspoon of sea salt in to flask 2. Stir to dissolve.
6. Use the beaker to fill the flasks to the very top…almost to overflowing.
7. Place an index card over the top of the fresh water flask.
8. Try to keep the card flat against the top of the flask and CAREFULLY invert the fresh water flask
over the top of the salt water flask as demonstrated...OVER THE PLASTIC CONTAINER!
9. Carefully and gently, remove the index card, keeping the tops of the two flasks together, and
observe.
10. Answer questions 1-3 in the question section
11. Repeat the above experiment, only this time, place the salt water in the top flask (step 7).
(you can carefully FLIP the two containers, keeping them tightly together)
12. Answer questions 4 – 5 in the question section
13. Repeat the above experiment (steps 1 – 11), only this time, use cold water (& blue food coloring)
and hot water (red food coloring). (NO SALT). Hot water goes in top flask first.
14. Answer questions 6-8 in the question section.
15. Rinse out all flasks and dry; return equipment to your plastic container. Clean up any and all spills.
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Lab #2 – OCE 101 – T/S/ρ Seawater
NAME:
Interactive Laboratory Questions
1. Which is more dense, salt water or fresh water? Explain WHY.
2. What happened when the fresh water in the top flask was allowed to mix with the salt water in
the bottom flask? Why?
3. Make a prediction about what will happen when you repeat this experiment with the salt
water up on top?
4. What did you observe when salt water was in the top flask? Why?
5. Make a prediction about what will happen when you repeat this experiment with the hot
and cold water.
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Lab #2 – OCE 101 – T/S/ρ Seawater
6. What did you observe when hot water was in the top flask?
NAME:
7. What did you observe when cold water was in the top flask?
8. Make a prediction about what would happen if you put HOT SALT WATER in the bottom
flask with COLD FRESH WATER in the top flask.
DEFEND YOUR PREDICTION.
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