68 | P h y s i c a l S c i e n c e L a b o r a t o r y I n v e s t i g a t i o n s
69 | P h y s i c a l S c i e n c e L a b o r a t o r y I n v e s t i g a t i o n s Procedures:
You will measure and calculate mass and volume, and compare densities.
Same Mass
1. Draw a table in which to record your values for this section. Do not fill in data until you have read the instructions for obtaining that data.
Same Mass
Measured Water Height
Predicted Sand Height
Measured Sand Height
Difference in Measured Heights
2. Fill one bottle with water, to just below the point where the bottle begins to taper.
Measure and record the height, in centimeters, to which the bottle is filled with water.
3. Predict and record the height to which you will need to fill a 2nd bottle with sand in order to have the bottle of water and the bottle of sand balance each other.
4. Place the bottle with water on one side of the simple balance, and place an empty bottle on the opposite side of the simple balance. Obtain some sand in your beaker and pour sand through the funnel into the empty bottle until it balances the bottle with water.
Fill Line
Pour sand into this one until it balances the water on the other side of the simple
balance Balance / scale by
improlux licensed in public domain
70 | P h y s i c a l S c i e n c e L a b o r a t o r y I n v e s t i g a t i o n s
5. Remove both bottles from the simple balance. Measure and record the height to which you filled the 2nd bottle with sand. Calculate and record the difference between the measured fill height of the water and the measured fill height of the sand.
Same Volume
6. Use the funnel to continue filling the bottle with sand until it is filled to the same height as the bottle with water. Lift both of the bottles a few times, with the bottle of water in one hand and the bottle of sand in the other hand. Record any differences you notice.
7. Draw a table in which to record the mass, volume, and density of the 3 bottles
containing different materials (air, water, and sand). Read the instructions for obtaining the data.
Same Volume
Type of Material Mass in Grams Volume (cm3) Density (g/cm3) Air
Water Sand
8. Use the platform spring scale to measure and record the mass in grams, of an empty water bottle, the bottle with water, and the bottle with sand. Note that we are using the mass of the empty bottle as the mass of air because we are not able to measure the mass of the air with the platform spring scale.
9. Calculate and record the volume in which you have air, water, and sand; this should be the same for each bottle. The height (h) is the measured water height from your first data table. Also calculate and record the density for each material.
71 | P h y s i c a l S c i e n c e L a b o r a t o r y I n v e s t i g a t i o n s Clean-up:
• Pour sand back into original container
• Rinse out the sand bottle
• Wash and completely dry your beaker
• Discard water outside (water the foliage)
• Place wet water bottles on the drying rack
Analysis:
1. Use ratios to compare the densities. Include all possible comparisons.
2. Explain why the same mass of sand and water had different fill heights.
General Questions:
1. Is it possible to have different amounts of mass fit into the same volume?
2. If two different objects have the same volume, they will also have the same mass.
(True or False)
3. If two different objects have the same volume, they will also have the same density.
(True or False)
4. Gold has a density of 19.3 g/cm3. Explain what the units mean.
5. Explain how density affects the weight of an object.
72 | P h y s i c a l S c i e n c e L a b o r a t o r y I n v e s t i g a t i o n s
Exercise 15 - Sinking & Floating
Student Learning Objectives:
Analyze relative density in relation to layers of liquids, and sinking & floating.
Materials:
1000 mL Graduated Cylinder 2 250 mL Beakers
2 Colors Food Coloring
Clear Corn Syrup (200 mL per group) Vegetable Oil (200 mL per group)
91% Isopropyl Alcohol (350 mL per group) Variety of Small Objects
Ice Cubes (from ice cube tray)
1000 mL Graduated Cylinder Schott Duran Beaker low form 250ml by Lucasbosch licensed under CC BY-SA 3.0
Introduction:
Sometimes fluids will remain separated such that one type of fluid is floating on top of another type of fluid. We see this if we add oil to water; the oil floats on the water. Whether a
particular material will float may depend on relative density. An object that is less dense than the fluid will float. An object that is more dense than the fluid may float under certain
circumstances.
Sample Small Objects Rubber band Metal paperclip Coated paperclip
Popcorn Pencil eraser
Bouncy ball Marble
73 | P h y s i c a l S c i e n c e L a b o r a t o r y I n v e s t i g a t i o n s Pre-Lab:
A. Describe what a fluid is.
B. What are some differences between a graduated cylinder and a beaker?
Procedures:
You will a variety of objects for whether they sink or float. The first activity may be completed as a class.
Density Gradient
1. Choose whether to sketch a diagram of the system and indicate the level at which objects settle, or draw a chart in which to record results. Sketch a cylinder with the layers of liquids, or draw a chart in which to list the level at which each object settles.
2. Obtain 200 mL of each liquid (corn syrup, water, vegetable oil, isopropyl alcohol), or observe as your instructor obtains these materials; the liquids must be added to the graduated cylinder in the correct order. The corn syrup may be poured directly into the graduated cylinder. The water may be obtained with a 250mL beaker, and 1-2 drops of food coloring may be added to allow the liquid to be more easily seen. Vegetable oil may be slowly poured into the
graduated cylinder. The alcohol may be obtained with a 250mL beaker, and 1-2 drops of food coloring may be added to allow the liquid to be more easily seen.
3. As each small object is chosen for testing, predict in your mind where the item will settle.
Share your predictions among your lab team. Then observe and record the position at which each item settles when dropped into the graduated cylinder.
Top of Alcohol Top of Oil Top of Water Top of Syrup Bottom
Penny Isopropyl Alcohol Vegetable Oil
Water Corn Syrup
74 | P h y s i c a l S c i e n c e L a b o r a t o r y I n v e s t i g a t i o n s Ice & Fluids
4. Fill one beaker with 150 mL of water and the other beaker with 150 mL of 91% isopropyl alcohol.
5. Predict whether the ice will be able to float in the water and/or the isopropyl alcohol.
Record your predictions.
6. Obtain 2 ice cubes and place one ice cube in each of the beakers. Record your observations for both the water and the isopropyl alcohol.
Clean-up:
• Pour the ice and liquids from the 250 mL beakers down the sink
• Clean and dry your beakers
• Follow instructor directions for clean-up of graduated cylinder materials
Fill up to the 150 mL line
Schott Duran Beaker low form 250ml by Lucasbosch licensed under CC BY-SA 3.0
75 | P h y s i c a l S c i e n c e L a b o r a t o r y I n v e s t i g a t i o n s Analysis:
1. Why is it important to add the liquids to the graduated cylinder in the correct order? Why do the liquids remain layered in this order?
2. Write a sentence which explains the locations small objects settled in the layers of liquids.
General Questions:
1. Based on your observations, which has a lower density, alcohol or water?
2. Ice and water are H2O molecules in different states. Why do you think ice (frozen H2O) floats in water (liquid H2O); why are the densities different?
76 | P h y s i c a l S c i e n c e L a b o r a t o r y I n v e s t i g a t i o n s