Name:_________________________
Lab: Salt Water vs Fresh Water
Problem:_Will
objects float the same way in salt water and fresh water?
Background Info / Research:
To calculate density, you need to measure the _____________ and ________________.
The formula for calculating density is Density = _________________________________
Welcome to the Dead Sea!
Most oceans contain 3% to 4% salt, while the water in the
Dead Sea is contains over 30% salt. The water is so dense
that it is impossible for a person to sink! You will float in
this water, no matter how heavy you may be! If you go out
swimming, kayaking, or canoeing there is no need for a
protective floating device.
What does the Dead Sea have that Black Moshannon
does not have?_______
Do most people sink or float in Black Moshannon? ____
Would you sink or float in the Dead Sea? ___________
Which water is more dense? _________________
Hypothesis:
If _______________________________________________________________________________________,
Then_____________________________________________________________________________________.
Experimental Set Up
Control Group:_________________________________________________________
Experimental Group:____________________________________________________
Variable:_______________________________________________________________
Materials:
1) Balance
2) Film Canisters
3)2 large beakers
4) Pennies, paperclips, beads
Procedure
1. Label the three film canisters #1, #2, and #3.
2. Fill a film canister to the top with water from the fresh water beaker. Use the dropper to make sure it is full.
Carefully pour the water into the graduated cylinder and measure the volume.
3. Record the volume on the data table. We will use this volume for all the canisters.
4. Add pennies and/or paperclips to an empty film canister #1 until the canister floats at the surface in a beaker
of fresh water. Use beads for any final adjustments. About ½ of the canister should be above the water and ½
should be below the water.
5. Draw a diagram of the floating canister #1 on the data table under fresh water.
6. Measure the mass of canister #1 and record it on the data table.
7. Calculate the density of canister #1
8. Put canister #1 into the salt water beaker.
9. Draw a diagram of canister #1 on the data table under salt water.
10. Go to the sink and carefully rinse all the salt off of canister #1.
11. Add pennies and/or paperclips to another empty film canister #2 until the canister floats in the middle of the
beaker of fresh water. Canister #2 should be completely under the surface of the water, but not touching the
bottom of the beaker.
12. Draw a diagram of the floating canister #2 on the data table under fresh water.
13. Measure the mass of canister #2 and record it on the data table.
14. Calculate the density of canister #2.
15. Put canister #2 into the salt water beaker.
16. Draw a diagram of canister #2 on the data table under salt water.
17. Go to the sink and carefully rinse all the salt off of canister #2.
18. Add pennies and/or paperclips to an empty film canister #3 until the canister just sinks to the bottom in a
beaker of freshwater. Make it float in the middle of the beaker first and then add one paperclip or bead at a time
until canister #3 just sinks to the bottom.
19. Draw a diagram of the floating canister #3 on the data table under fresh water.
20. Measure the mass of canister #3 and record it on the data table.
21. Calculate the density of canister #3.
22. Put canister #3 into the salt water beaker.
23. Draw a diagram of canister #3 on the data table under salt water.
24. Go to the sink and carefully rinse all the salt off of canister #3.
Record Data:
Canister
1
2
3
Mass (g)
Volume (mL)
Density (g/cm3)
Freshwater
Salt Water
Canister #1
Canister #2
Canister #3
Analysis:
1. Compare the position of canister #1 in the freshwater and salt water beakers.
__________________________________________________________________________________________
__________________________________________________________________________________________
2. Compare the position of canister #2 in the freshwater and salt water beakers.
__________________________________________________________________________________________
__________________________________________________________________________________________
3. Compare the position of canister #3 in the freshwater and salt water beakers.
__________________________________________________________________________________________
__________________________________________________________________________________________
4. Did the volume of the film canister change at all? _________ How do you know? ____________________
__________________________________________________________________________________________
__________________________________________________________________________________________
5. Did the mass of the any of the canisters change when they were moved from the freshwater to the saltwater
beaker? _________
Explain.__________________________________________________________________________________
__________________________________________________________________________________________
6. If neither the mass nor the volume of the canisters changed, why are canisters floating in different positions?
__________________________________________________________________________________________
__________________________________________________________________________________________
__________________________________________________________________________________________
7. Why does an object float? Explain using density.
__________________________________________________________________________________________
__________________________________________________________________________________________
8. Why does an object sink? Explain using density.
__________________________________________________________________________________________
__________________________________________________________________________________________
9. What does this lab tell you about the density of fresh water and salt water? Use data from the experiment to
explain your answer.
__________________________________________________________________________________________
__________________________________________________________________________________________
__________________________________________________________________________________________
__________________________________________________________________________________________
__________________________________________________________________________________________
10. Compare the buoyancy of freshwater and salt water. Use data from the experiment to explain your answer.
__________________________________________________________________________________________
__________________________________________________________________________________________
__________________________________________________________________________________________
__________________________________________________________________________________________
__________________________________________________________________________________________
Conclusion: Write as a paragraph. Do NOT number the sentence answers. Write your conclusion on a sheet of
yellow composition paper.
1.
2.
3.
4.
5.
6.
7.
Write a thesis statement based on the hypothesis.
Accept or reject hypothesis.
Use information from the control group data as support for accepting or rejecting the hypothesis.
Use information from the experimental group as support for accepting or rejecting the hypothesis.
List at least one source of error.
List at least one improvement that could be made.
Write a summary (closing) sentence.