Name: ______
Date: ______
Class: Earth Science B
Teacher: Mrs. Nakamura
Virtual Lab U2L8, Sea Water Density
Getting Started:
1)Make sure that you have the “Virtual Earth Science CD” installed on your computer and that it works. If you are having issues contact tech support at 800-382-6010.
2)Look over the sheet below.
3)WATCH Mrs. Nakamura’s LL before completing the lab! It will show you how to manipulate each of the item
4)Complete the blue shaded areas in each section.
5)Scoring for each section is at the very bottom of this worksheet.
6)NOTE: I suggest playing with each of the items and testing out how to manipulate everything before starting the lab. Once starting the lab you CANNOT EXIT OR RESET the lab. It will reset all the values. So test it out. Then fully exit the virtual simulation. Then restart it when you are ready to do the full lab.
7)Don’t forget units of measure on the answers
8)Points for each section are at the bottom of the worksheet.
Equations you need:
Background:
Only a small part of the water on Earth is fresh water. Most of the water on Earth is salt water. Not all of the salt water has the same salinity and there are differences in the density of the water due to depth in the ocean and temperature of the water. In this lab, you will determine the density of fresh water and different types of seawater. You will also measure the density of different objects that we might find floating in the ocean, and mix waters as might happen with deep ocean or surface currents.
Section 1: Prediction
1)Start Virtual Earth Science and select Seawater Density from the list of assignments. The lab will open in the Density laboratory.
2)The laboratory will be set up with 4 graduated cylinders of water on the counter, each with a ball of ice suspended over it.
- Each of the ice balls is exactly the same size.
- One of the cylinders will have fresh water
- The rest have salt water of different densities in them.
3)You are going to make a prediction. You will measure the densities of the waters and rank them from LEAST dense to MOST dense based on visually inspecting the cylinders.
4)Column A: Click on the top of the each of the 250 mL graduated cylinders to see a zoomed in view of the level of the fluid. Record the volume of the water in the Data Table below under the column “Initial Volume of Water”
5)Column B: Then click the blue All button to let all the balls fall into their cylinders. Look at the close up view windows. Record the new volumes of the waters.
6)Column C: Subtract initial volume from displaced and record value.
7)don’t forget units of measure on the answers
Column A / Column B / Column CInitial volume of water (mL) / Displaced volume of water(mL) / difference(mL)
displaced – Initial
Example / 228 mL / 240 mL / 12 mL
1
2
3
4
Quality answer of 2-3 sentences. Explain your thinking. Think about these things; did the original balls have the same densities to start, if so what does that tell you about the densities of the water in the different cylinders?
The less water displaced the higher the ball floats. The higher the ball floats the denser the water.
1)Question: Based on the above information and what you observed from the ice balls floating in the cylinders make a PREDICTION about the densities of the fluids. Rank them in order from least to greatest.
Section 2: Density of Ball
Answer this question with detail 2-3 sentences. Describe how you found the volume. SHOW the formula you are using and SHOW the math that you use to find the answers. Be specific2)Determine the density of the ice ball
(don’t forget units of measure)
Remember that the ball has to be totally submerged to accurately measure its volume.
Section 3: DATA
Make sure you completely fill in the table with the data you are gathering. Make sure you use the measurements as part of your answers. Ex: g, mL. You will lose points if you forget them. In science this is extremely important and one scientist forgot to include his unit of measurements and it resulted in a crashed MARS rover.
You will now calculate the actual densities of the different water samples
1)Column D:First weigh the mass of the large empty beaker. Drag the beaker on the counter to the balance and record its mass in column D.
2)Drag the ice ball from the cylinder to the Solid Return hole on the counter to dispose of the sample.
3)Column E:Pick up the first cylinder filled with water and pour it into the empty beaker. Record the mass in column E.
4)After recording the mass, drag the beaker on top of the first cylinder, and the water will pour back into the original cylinder.
5)Repeat step 3 & 4 until each item is measured and recorded.
6)Column F:Determine the Mass of the water by subtracting theMass of Empty Beaker (g) from Mass of Beaker and Water (g). Record in column F.
7)Column G:Get the Initial volume of water (mL) from Column A in the first table.
8)Column H:Calculate the density of each water sample. Use the density formula and Mass of Sample (g) and Volume of Water (mL)
Don’t forget your units of measure in the columns!
Column D / Column E / Column F / Column G / Column HSample / Mass of Empty Beaker (g) / Mass of Beaker and Water (g) / Mass of Sample (g) / Volume of Water (mL) / Density (g/mL)
Cylinder 1 Water
Cylinder 2 Water
Cylinder 3 Water
Cylinder 4 Water
Mixed
(you will do this row in section 6)
Section 4: Analyzing data
Quality answer of 2-3 sentences. Explain your thinking. The water with the lowest density is the fresh water sample. The other samples are of the densities of sea water ranging from the surface to the deep ocean.3)Were you correct in your predictions of the different densities of the waters? Look back at question #1.
Compare your original prediction to your results from column H.
Applying Concepts You saw how ice floats in all different types of water. Now test different solids in your waters to see if you can find some that float and some that sink. (Minimum5 samples, but you can do more)
Sample Name / Float/sink
1
2
3
4
5
Quality answers 2-3 sentences.
4)Think about the different types of things that are disposed of into bodies of water. What does this teach you about littering?
Think about what you tested. What floated and what sank? Describe them and make connections about the density of each object in comparison to the density of the water. How does this apply to items that might get tossed into the oceans?
Section 5: Oil Water experiment
1)Make sure the fluid dispenser is above the last cylinder on the lab bench.
2)Use the Up and Down arrows on the control panel to toggle through the options of fluids to use in the lab.
3)Select Sea Water. Click the button underneath that display to select the amount of fluid to be added to the cylinder.
4)Click the fill button to release the Sea Water into the cylinder.
5)Now choose Car Oil and click the button underneath that display
6)Click the fill button to release the Oil into the cylinder.
Quality answers 2-3 sentences.5)What happened when you poured the oil into the sea water?
6)What does this teach you about oil spills in the ocean?
Think about what you have seen in the news about oil spills and connect this to what you are seeing in the experiment.
Section 6: Mixed Water experiment
1)Make sure the fluid dispenser is above the last cylinder on the lab bench.
2)Click the blue handle at the bottom of one of the cylinders to empty the contents of the cylinder.
3)Fill half the cylinder with Water and fill the other half with Sea Water.
4)The liquids are automatically mixed, which is what would happen with real ocean currents.
5)Complete the row for Mixed sample in section 3
Column D / Column E / Column F / Column G / Column HQuality answers 2-3 sentences.
7)What do you notice about the resulting density of the mixed water? You are mixing two liquids of different densities. What is the density of this mixture and how did it compare to the other samples?
8)Think about water on this planet where might you find salt and fresh water mixing?
Section 7: Conclusion
Draw a Final Conclusion: Here are some items to include in your final conclusion- Using specific details from your data, describe to me what you learned of the different densities of water, the different densities of the items you tested.
- Explain how density, mass, and volume determined whether an item floated or sank.
- Something else to consider when writing up your final conclusion is what did you learn?
Mrs. Nakamura’s Scoring Guide (don’t worry about filling it in)
Items / PossiblePoints / Earned / Teacher Comments
Prediction data table / 2
Q1 / 1
Section 2 / 1
Section 3 data table / 5
Q3 / 2
Applying concepts data table / 1
Q4 / 2
Q5 / 1
Q6 / 1
Q7 / 1
Q8 / 1
-1 / -1 if units of measure are not used
Conclusion / 1
Total possible with extra credit 19 / 17