*Lesson 7.2:  Why is there an increase in the volume of ocean water?

Part 1: Investigation: Which type of ice is contributing to sea level rise?

1. From the Edpuzzle you learned there are two types of ice in the cryosphere: land ice and sea ice.

2. Write a claim stating which type of ice you think will contribute to sea level rise.

Both types of ice will contribute to sea level rise.

1. Write a claim stating what you think will happen to the freshwater as it melts into the saltwater ocean in your model.

the freshwater will mix with the saltwater in the ocean, rendering it unusable.

MATERIALS:

• 250-mL beaker

• NaCl

• Weighing boat

• 2 100-mL graduated cylinders

• 2-Blue Colored Ice Cubes

• Funnel

PROCEDURE:

1. Make an ocean water solution.
   1. Mass 0.5 g of NaCl.  Place the solid NaCl into a 250-mL beaker.
   2. Using a graduated cylinder, add approximately 200 mL of cold tap water.
   3. Stir the solution to dissolve the NaCl.

2. Label one graduated cylinder of ‘sea ice’ and the other graduated cylinder ‘land ice’.

3. Pour 70 mL of ocean water into each of the graduated cylinders.  

4. Place one blue ice cube into the ‘sea ice’ graduated cylinder.  You may need to break the ice cube into two pieces for the ice to enter the graduated cylinder.  See your instructor for help and tools.

5. Record the initial volume, Vi, of the graduated cylinder of the ‘sea ice’ to the tenth spot.

6. Place a funnel into the top of the ‘land ice’ graduated cylinder.  Place one blue ice cube into the funnel.  Record the initial volume of the graduated cylinder accurately. 

7. Proceed to Part 2, read and answer questions about ‘The Hydrosphere, Cryosphere, and Types of Ice’ while the ice melts.

8. After all of the ice melts, record the final volume, Vf, of each graduated cylinder. 

9. Make observations regarding the position of the ‘blue’ melted ice.

10. Calculate the change in volume, ᐃV, for each using the equation, ᐃV = Vf - Vi: 

DATA TABLE PART 1: VOLUME OF SEA ICE AND LAND ICE

	SEA ICE	LAND ICE
Initial Volume, Vi	79.5 mL	71.0 mL
Final Volume, Vf	79.5 mL	78.0 mL
Change in Volume, dV
Observations of Melted Blue Water

Part 2: The Hydrosphere, Cryosphere, and Types of Ice

Read more about the hydrosphere and cryosphere.

Water on Earth is in the hydrosphere. This includes all forms of water; solid, liquid, and gas, on Earth. Earth’s hydrosphere cycles the finite amount of water on Earth. Oceans cover nearly three-quarters of Earth’s surface and hold 97 percent of the total water volume on Earth. (Doyle, et al., 2015) Freshwater, both solid and liquid, make up the last 3 percent. Solid water, or ice, has its own designation within the hydrosphere called the cryosphere. Scientists have learned a lot about Earth’s history, atmospheric composition, and temperatures from studying the cryosphere. 

There are two types of ice in the cryosphere: land ice and sea ice. Land ice is freshwater ice and includes glaciers, icebergs, and sheet ice because each originates on land.  Sheet ice, is located around Earth, but 99% of it is located in the Antarctic and Greenland ice sheets. (National Snow and Ice Data Center [NSICD], 2020) An ice sheet forms on land when the annual snowfall exceeds the annual snowmelt. (NSIDC, 2019) Ice sheets take thousands of years to form and can be thousands of feet thick and tens to thousands of miles across. (NSIDC, 2019) Ice sheets are able to flow, or move, and move out in all directions. Ice sheets are continental glaciers. Sea ice is frozen seawater floating on its surface. Sea ice forms from ocean water. Sea ice contains very little salt. Sea ice forms seasonally and can cover millions of square kilometers each polar season. (NSIDC, 2019) While sea ice is found in both the Arctic and Antarctic, some of the ice lasts year after year in the Arctic, while in the Antarctic the majority melts and reforms each season.

Land ice in Greenland	Sea Ice: Arctic (top) & Antarctica (bottom)

1. Answer the following questions from the reading.

2. What is the hydrosphere?

3. What are the states H2O occurs on Earth?

4. What percentage of the Earth is covered by ocean water?

5. What percentage of the total volume of water on Earth is held in the ocean?

6. What percentage of water as solid and liquid is freshwater?

7. What is the cryosphere?

8. What two locations contain the majority of the land ice or sheet ice?

9. Is sheet ice fresh or saltwater?

10. How is sea ice different than land ice?

Continue onto Part 3, if your ice is not melted in Part 1.

Part 3: Investigation: What happens when liquid water is heated? 

1. Write a claim stating what you think happens when liquid water is heated.

MATERIAL

• 600-mL Beaker

• 125-mL Erylenmeyer Flask (some classes may have 250-mL Erylenmeyer Flask)

• One hole rubber stopper with 10 mL glass pipette

• Hot plate 

• Thermometer

PROCEDURE:

1. Look at the 10-mL pipette and notice the scale.  Readings will be taken to the hundredth spot.  Use the scale that is from 0 → 10 in the fine print. Be confident in your ability to read the scale.  

2. Place the 10-mL pipette carefully into the hole of the rubber stopper.  Be careful since the pipette is glass and the set-up is clumsy.

3. Fill the Erlenmeyer flask with tap water to the top of the rim.

4. Place the stopper with the 10 mL pipette onto the Erlenmeyer flask with water. If done correctly, water will be observed on the scale of the pipette.

5. Record the water level of the pipette accurately using the fine print scale to the hundredths spot.  This is the initial water level.

6. Pour approximately 200 mL of tap water into a 600-mL beaker. This is your water bath.

7. Immerse the Erlenmeyer flask inside the 600-mL beaker water bath.

8. Record the temperature of the water bath. This is also the temperature of the water in the flask.  This is your first reading.

9. Place on the hot plate. Turn the hot plate to medium..

10. Record the level of the water in the pipette and the temperature of the water bath.  Use two different temperatures of the water bath - approximately 50oC and 70oC.

11. Clean up all materials from Part 1 and Part 3.

DATA TABLE PART 2: VOLUME OF HEATED WATER

Temperature (C), T	Pipette Volume (mL), V
22	1.30
25	1.35
28	1.40
30	1.45
32	1.50
36	1.60
38	1.65
41	1.90
45	2.10
51	2.55
^volHeatedWater

1. Create a scatterplot graph with a trendline where you compare volume and temperature where temperature is your independent variable.  Make sure your graph has a title and axes are labeled with the correct unit. (insert below)

type: line
labels: [22,25,28,30,32,36,38,41,45,51]
series:
  - title: Pipette Volume (mL), V
    data: [1.30,1.35,1.40,1.45,1.50,1.60,1.65,1.90,2.10,2.55]
width: 80%
beginAtZero: true
bestFit: true
bestFitTitle: Line of Best Fit
bestFitNumber: 0

1. What is the relationship (direct and inverse) between volume and temperature?  Explain using the data from the graph.   Volume is directly related to temperature

2. Using the equation ΔV = βV0ΔT where your initial volume is 150 mL and using your data from above, calculate the thermal volume expansion coefficient, β.

\[\Delta v = 1.25$$ $$\Delta t = 29$$ $$1.25 = \beta * 1.30 * 29$$ $$\beta = \frac{1.30*29}{1.25}$$ $$\beta = 30.16\]

1. If the thermal volume expansion coefficient, β for water is 2.10 x 10-4 oC–1 at 20oC, then what is your experimental error?

Use the equation:  % error = expermental value - actual valueactual value x 100

\(error = \frac{30.16 - }{}\)

1. What can you account for the experiment error?  (Hint- Please do not use human error as your explanation.  Think about the error that is intrinsic to the lab setup).

   we didnt use pure water, instead we used tap water which can vary in expansion cooeficients. our Erlenmeyer flask may have not been perfectly watertight, resulting in incorrect results

Part 3 - Analysis Questions

1. Consider the water in the Erlenmeyer flask, what was held constant - mass, volume, number of particles, density? 

number of particles

1. What was the total change in volume in pipette?

0.4 mm

1. What was the total change in temperature?

29 C

1. What is the relationship between volume and temperature in this experiment?

direct

1. Is the density of water always 1g/mL? Support your answer with evidence.

no, due to variances in temperature, water is not always 1g/mL

1. This experiment shows thermal expansion of water.  We draw water molecule showing covalent bonds and lone pairs the same way whether water is a solid, liquid or gas.  The structure of the molecules do not change.  What is happening when water molecules are heated to result in this expansion of volume?

the water molecules get farther apart because they are moving faster

1. Using your knowledge of the structure of water molecules, draw a model of 5 water molecules at room temperature and water at a warmer temperature. 

Model of 5 Water Molecules at room temperature	Model of 5 Water Molecules at higher temperature

Concluding Thoughts:

1. Melting land ice accounts for 40% of the rising sea level.  Thermal expansion of water accounts for 60% of the rising sea level.  In your own words, why is there an increase in the sea level? 

NEXT STEPS:

1. Reflect on today’s question: Why is there an increase in the volume of ocean water?

2. Open up the IMT for this unit, complete all boxes for lesson 2

3. Make sure all parts of the L7.2 student sheet are complete & complete the check for understanding on Schoology.**

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Last update: June 5, 2023
Created: June 5, 2023