Earth Systems
Standard 4, Objective 3
Title: Sea Water Lab
Description: This lab is a “station” lab where students move from one small experiment to another. There are seven stations dealing with properties of sea water.
Materials:
Note: you may want to set up more that one set of materials at each station so that groups can be smaller.
Station 1: 2 baby food jars, red food coloring, hot plate, large beaker, oven mitt, laminated index card or piece of plastic sheet, pie tin or cookie sheet
Station 2: 2 immersion thermometers, 2 styrofoam cups, ice, rock salt
Station 3: 2 liter pop bottle with 5 holes (melted in with hot nail) up the side in a row, masking tape, sink
Station 4: test tube, test tube rack, 3 dropper bottles, red and green food coloring, fresh water, concentrated salt solution (color red), weak salt solution(color green)
Station 5: 2 pill bottles, concentrated salt solution, fresh water, triple beam balance
Station 6: Large beaker, crushed red ice (made from red food color in water)
Station 7: Plastic box, water, holes from hole puncher
Background:
This activity demonstrates a variety of sea water properties. Density is addressed by station 1, 4, 5, and 6. The ocean is a layered system with the coldest, saltiest water at the bottom because it is most dense.
Station 2 illustrates a property of salt water that is meaningful in polar areas. Water with salt in it has to be much colder for it to freeze.
Station 3 shows how water pressure increases with depth.
Station 7 shows that waves do not move water but wind does.
Time Needed: 110 minutes, including time for discussion and for students to answer analysis questions.
Procedures:
1. Time needed for set-up may seem overwhelming but once you have done it the first time, keep the stuff together and it will be much easier the next time.
2. Make red ice a day before the lab.
3. Make cardboard cards with the station numbers on them.
4. Run off student sheets.
5. Set up stations:
Station 1: Set up two stations for this one. Place them on a counter near a sink. Have the hot plate nearby to heat the red water in a large beaker. Students should perform the experiment in the pie plate or cookie sheet so that if they spill, it doesn’t go anywhere. Stream tables can be used also but are harder to empty.
Station 2: Set up two stations. The thermometers should be in the ice in labeled cups. Add quite a bit of salt to cup #2.
Station 3: Set up two stations. Needs to be next to a sink so students can fill the bottle with the tape on and then rip the tape off so that the water goes in the sink. The liter bottle needs to be prepared by melting with a hot nail 4 or 5 holes up the side so that a single piece of tape can cover them.
Station 4:
Set up 3 stations for this one because it is the most time consuming. The solutions need to be available and students will need a disposal beaker when they are done.
Station 5:
Set up two stations of this one because it doesn’t take long.
Station 6
Set up two stations and have a bucket for disposal. A Styrofoam cup will keep the red ice frozen for the period.
Station 7
Set up two stations and do not give students many of the paper circles at a time. They tend to waste them.
6. If students do not finish in the time you have, demonstrate each experiment (or have a student do it) so that each student has data to record for each station.
Scoring Guide
Students complete each station personally……………………………….4
Students record data accurately…………………………………………….4
Students correctly answer analysis questions……………………………4
Title: Sea Water Lab name______
Purpose: To observe and experiment with the properties of seawater.
Procedure:
1. Seven stations have been set up. Visit each one and record the data.
2. Answer the analysis and conclusion.
Station 1-Hot and Cold Water
1. Use the baby food jars. Set one in the pie tin and fill it with cool water.
2. Fill another jar with hot, red water from the beaker. Place a laminated card over the top.
3. Carefully flip the covered jar on top of the first jar. Gently pull the card out from in between them. Observe and draw what happens.
4. Repeat, this time place the hot water on the bottom, cool water on top.
Data: drawings
Station 2-Water Temperature
1. The thermometers are sitting in ice. Thermometer 1 is just ice, thermometer 2 is ice with salt in it.
2. Ice melts in a similar fashion to water boiling. The temperature remains at the melting point until all the ice is gone.
3. Write down the melting point of the ice and the ice and salt:
Data: thermometer 1______thermometer 2______
Station 3-Water Pressure
1. Find the holes on the side of the pop bottle. Dry them and place a long piece of masking tape over them.
2. Fill the bottle with water and place it on the edge of the sink.
3. Quickly pull the tape off the holes and allow them to drain into the sink.
4. Draw the results:
Data:
Station 4-Water Density
1. Pour 10 ml of red, salty water into a test tube.
2. Slowly, drop by drop, add an equal amount of fresh clear water. If a two layer system hasn’t formed, start over.
3. Add several drops of the green water until you can see where it floats.
4. Draw and label your test tube. Color the water as you see it.
Data:
Station 5-How Much Denser?
1. Add 25 ml of fresh water to the vial labeled “fresh water. Mass the vial containing 20 ml of fresh water. ______g
2. Add 25 ml of salt water to the vial labeled “salt water”. Mass the vial containing 20 ml of salt water. ______g
Station 6-Cold Water
1. Add 300 ml of water to the beaker. Place it in front of the white paper.
2. Add a piece of red ice. Observe and draw the beaker.
Data:
Station 7-Waves
1. Add several paper circles to the water in the plastic box.
2. Gently tap the side of the box to produce waves. Observe the movement of the paper circles.
3. Blow across the surface of the water. Record the movement of the circles now.
Data:
wave movements:
wind movements:
analysis for “Sea Water Lab”
Station 1
1. Where did the warm water want to be? The cold?
2. Why does water behave this way?
3. Where will cold water be in the ocean?
Station 2
4. What does salt do to the melting point of ice?
5. Why do we put salt on the roads?
Station 3
6. Which hole pushed water out the fastest and furthest?
7. Why?
8. Where in the ocean will pressure be the highest?
Station 4
9. Which color water was densest?
10. What caused it to be most dense?
11. How much salt must have been in the green water?
12. When the sun evaporates water from the ocean it makes the seawater saltier. What would that water do next?
Station 5
13. Why was it important to use the same amounts of each type of water?
14. Which weighed the most for its size?
Station 6
15. Arrange these in order starting with the least dense: tap water, ice, melting ice water.
16. As ice melts from the polar regions, where would it go next?
Station 7
17. Where will a ball floating in a wave pool go?
18. Where will a ball floating in a pool go if the wind blows?
19. Do waves move water?
Conclusion: (3 things you learned)