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Name______________________________
Density
Purpose: To explore the property that allows objects to float.
Question: What allows an object to float?
Background Information: Atoms and molecules are always in motion. When temperature increases, the
energy of the atoms and molecules also increases, which results in an increase in motion.
Solids are substances that have tightly packed atoms and molecules. They are so tightly packed, that they
vibrate when they move. They have the lowest energy.
Liquids have more energy. They are more loosely packed, and the atoms and molecules can slide past each
other.
Gases have the most energy. Except for occasional collisions, the atoms and molecules are not in contact with
each other.
Middleschoolchemistry.com
Density is the amount of matter in a specific volume or amount of space. It is the relationship between the
mass of the substance and how much space it takes up (volume). It is a measure of how tightly packed atoms
and molecules are in a substance.
Substances of higher density will sink below substances of less density.
Density is a characteristic property of a substance.
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The mass of atoms, their size, and how they are arranged determine the density of a substance.
Density equals the mass of the substance divided by its volume; D = m/v.
Objects with the same volume but different mass have different densities
Summarize this information below:
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Materials:
Baby oil
Alcohol
Graduated cylinder
Vinegar
Triple beam balance
Calculator
Syrup
Beaker
Water
Spheres of different sizes
Procedure: Part 1 – Observing the liquids
1. Observe each liquid and record your observations.
2. Record the similarities and difference between the liquids.
Data: Part 1 – Observing the liquids
Observations of Liquids
Liquid 1:
Liquid 2:
Liquid 3:
Liquid 4:
Liquid 5:
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Similarities
Differences
Questions: Part 1 – Observing the liquids
1. What causes some liquids to be thicker than others?
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2. How might the molecules of the thicker liquids differ from the thinner liquids?
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Procedure: Part 2 – Combining the liquids
1. Very slowly, pour 50 ml of each liquid into the beaker, one liquid at a time.
2. Let the liquids settle.
3. Record your observations.
Data: Part 2 – Combining the liquids
Observations of Combined Liquids
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Questions: Part 2 – Combining the liquids
1. Why do you think one liquid went to the bottom of the beaker?
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2. If one liquid is denser than all the other liquids, what can you say about the atoms or molecules in that
liquid?
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3. If the molecules are more tightly packed together in the densest liquid, are there more or less atoms or
molecules in each unit of space than compared to the molecules in the thinnest liquid?
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4. Of the liquids you observed, which do you think have a high density? Explain your answer.
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5. Will the liquids separate like this, no matter the order in which you pour them into the beaker? Explain
your answer.
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Procedure: Part 3 – Calculating Density
1.
2.
3.
4.
Use the triple beam balance to find the mass of your EMPTY graduated cylinder. Record.
Add 25 ml of the first liquid.
Find the mass of the graduated cylinder + the liquid. Record.
Subtract the mass of the graduated cylinder from the mass of the graduated cylinder + the liquid.
Record.
5. Calculate the density of the liquid. D= M/V
6. Repeat for all liquids.
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Data: Part 3 – Calculating Density
Liquid
Mass of graduated
cylinder (g)
Density of the Liquids
Mass of graduated
Mass of
cylinder + liquid (g)
Liquid (g)
Volume of
Liquid (ml)
Density (g/ml)
Graph the density data. What type of graph is most appropriate for this type of information? _______
Why? _______________________________________________________________________________
Procedure: Part 4 – Float or Sink
1. Observe each of the spheres.
2. Predict whether the sphere will sink or float. Record your prediction. Explain your reason.
3. Drop the spheres, one at a time, into a beaker of water. Record what they actually do.
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Data: Part 4 – Float or Sink
Sphere
Sink or Float?
Sink or Float Prediction
Reason
Actual
Questions: Part 4 – Float or Sink
1. What can you say about the atoms or molecules in a marble compared to the atoms or molecules in a
wooden ball?
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2. How would you describe the density of the metal ball?
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3. How would you describe the density of water? Why?
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Conclusions: Apply what you have learned to the Earth.
1. You have seen that denser materials sink. In the interior of the Earth, where do you think the densest
substances will be? Explain your answer.
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2. Which layer of the Earth is the densest? Why?
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3. How would you describe the density of the mantle compared to the other layers? Explain your answer.
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4. Each of the layers of the Earth is composed of different materials and has a different thickness. When
the Earth was forming, all of the materials were mixed up. What do you think happened to the
materials inside the Earth over time?
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5. How does density affect the composition and order of Earth’s layers?
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Think about it: How can the density of the Earth’s layers affect the movement of the plates?
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M. Poarch 2013
science-class.net ( adapted from Astro-Venture: Geology Educator Guide astroventure.arc.nasa.gov)
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M. Poarch 2013
science-class.net ( adapted from Astro-Venture: Geology Educator Guide astroventure.arc.nasa.gov)
Permission granted to copy for non-profit, educational use only.