Key Concepts

A submerged thing displaces a volume the liquid equal to the volume of the object.One milliliter (1 mL) of water has a volume the 1 cubic centimeter (1cm3).Different atoms have different sizes and also masses.Atoms top top the periodic table are arranged in order according to the number of protons in the nucleus.Even though an atom may be smaller sized than one more atom, it might have more mass.The fixed of atoms, their size, and also how they are arranged determine the density of a substance.Density amounts to the massive of the object separated by that volume; D = m/v.Objects v the very same mass however different volume have different densities.

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Summary

Students usage the water displacement method to uncover the volume of various rods that all have actually the same mass. They calculate the density of each rod, and use the characteristic thickness of each material to determine all five rods. Climate students consider the relationship between the mass, size, and also arrangement of atom to describe why different rods have various densities. Students will certainly be briefly presented to the regular table.

Objective

Students will be able to explain that materials have characteristic densities due to the fact that of the various mass, size, and also arrangement of their atoms. College student will have the ability to use the volume displacement technique to discover the volume of one object.

Evaluation

Download the student task sheet, and distribute one every student as soon as specified in the activity. The activity sheet will serve as the “Evaluate” ingredient of each 5-E class plan.

Safety

Make sure you and your student wear appropriately fitting goggles.

Materials because that Each Group

Set the 5 different rods that all have actually the very same massGraduated cylinder, 100 mLWater in a cupCalculator

Notes around the materials:

For this lesson friend will require a collection of 5 solid rods, each with the very same mass, same diameter, yet a different volume. Each rod is do of a different material. Over there are several versions of these rods easily accessible from different suppliers. This task uses the same Mass Kit from Flinn scientific (Product #AP4636) but can be adjusted to any collection of same mass rods. Because there space only five samples in the same Mass kit, you may need 2 kits so the each team can work with a sample.

This graph will aid you recognize each rod. Execute not reveal this details to the students. Lock will discover the identification of each rod and the station relationship in between the density and the length of every rod later in this lesson.

Table 1. Physics properties for solid cylinder unkowns.SampleMaterialApproximate thickness (g/cm3)Relative lengthSmallest metalShiny gray metalDark grayTall off-whiteTallest white
Brass7.5shortest
Aluminum3.0
PVC1.4
Nylon1.1
Polyethylene0.94longest

Engage

Show students 5 rods that have actually the very same mass however different volumes.

Show students the five rods and explain that they all have the exact same mass. Then host up the longest, middle-sized, and also shortest rods and also remind students the they have actually the exact same mass.

Ask students to do a prediction:

Which stick is the many dense? least dense? In between?

Students may reason that since the massive of every rod is the same, the volume of every rod must have something to perform with the density. Some may go so far regarding say that the rod with the the smallest volume must have actually the highest possible density, since the very same mass is packed right into the smallest volume. Or that the rod through the biggest volume must have actually the shortest density, since the exact same mass is spread out out end the biggest volume.

Tell student that favor the cubes in the ahead activity, they will require to know the volume and mass of every of the samples. They will likewise calculate the thickness of every sample and use this worth to figure out which product each rod is do of.

Show an animation and also demonstrate how to measure up volume utilizing the water displacement method.

Project the computer animation Water Displacement.

Play the animation as you demonstrate the water displacement an approach using a cup the water, a i graduated cylinder, and a rod, the means students will perform in the activity. Use the dark gray plastic sample so that students can see that better.

Volume

Demonstrate what student will do by pouring water native a cup right into a 100-mL graduated cylinder until it reaches a height that will certainly cover the sample. This is the “initial water level.”

Tell students that the surface ar of water in a tube may not be totally flat. Instead, the surface may curve in a shallow U-shape called the meniscus. As soon as measuring, read the line simply at the bottom the the meniscus.

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Tilt the i graduated cylinder and slowly slide the sample right into the water. Host the i graduated cylinder upright. Record the level of the water. Point out that this is the “final water level.”

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Tell students that you desire to find out just how much the water level changed. Subtract the initial water level indigenous the last water level to uncover the volume of the rod.

Volume the sample = final water level − early water level.

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Explore

Have students calculation the thickness of five various rods and also use the characteristic building of thickness to correctly identify them.

Note: The densities for the 3 plastics room similar, for this reason students should be an extremely careful once measuring your volume utilizing the water displacement method. Also, that is daunting to measure up the volume the the the smallest rod. Give students a hint that it is in between 1.5 and also 2.0 mL.

Question to investigate

Can you use density to determine all 5 rods?

Materials for each group

Set that five different rods that all have actually the very same massGraduated cylinder, 100 mLWater in a cupCalculator

Teacher preparation

Use a long-term marker to note the five rods through letters A, B, C, D, and E. Keep track of i beg your pardon letter corresponds to i m sorry sample there is no letting student know. If you room using two or much more sets of rods, be certain to mark each sample of the same material with the very same letter. After a group finds the volume that a sample, they need to then pass that sample to an additional group till all groups have discovered the volume that all 5 rods. Because that the longest sample, i beg your pardon floats, students can use a pencil to gently press the sample simply beneath the surface of the water to measure its full volume.

Procedure

VolumePour enough water from your cup into the i graduated cylinder to with a elevation that will certainly cover the sample. Read and also record the volume. Contempt tilt the graduated cylinder and carefully place the sample right into the water. Place the graduated cylinder upright on the table and also look in ~ the level that the water. If the sample floats, usage a pencil to gently push the peak of the sample simply under the surface ar of the water. Record the number of milliliters because that this final water level.

Find the quantity of water displaced by individually the early level the the water from the last level. This volume equals the volume the the cylinder in cm3.

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Record this volume in the chart on the activity sheet.Remove the sample by pouring the water back into your cup and taking the sample out of your i graduated cylinder.DensityCalculate the density using the formula D = m/v. Document the density in (g/cm3).Trade samples v other groups until you have actually measured the volume and calculated the density of all 5 samples. Table 2. Volume, mass, and also density for unknowns A–HSampleInitial water level (mL)Final water level (mL)Volume that the rods (cm3)Mass (g)Density (g/cm3)ABCDE
15.0
15.0
15.0
15.0
15.0
Identify the samplesCompare the worths for thickness you calculated come the values in the chart. Then compose the letter name for every sample in the chart.

Note: The densities college student calculate might not be precisely the exact same as the provided densities in the chart. Together students room working, examine their worths for volume to be sure that they room using the difference between the final and initial water levels, not just the last level.

Table 3. Volume, mass, and also density because that unknowns A–HMaterialApproximate thickness (g/cm3)Sample (Letters A–E)BrassAluminumPVCNylonPolyethylene
8.8
2.7
1.4
1.2
0.94

Discuss whether students’ worths for thickness support their predictions native the beginning of the lesson.

Discuss student values for thickness for each of the samples. Point out that various groups may have different values because that density, yet that most of the values are close to the values in the chart.

See more: What Is The Difference Between A Postulate And A Theorem? Difference Between Postulate And Theorem

Ask students:

Each group measured the volume that the same samples. What room some reasons that groups might have different values because that density?Students must realize that tiny inaccuracies in measuring volume can account for distinctions in density values. Another reason is the the i graduated cylinder, itself, is not perfect. So there is always some uncertainty in measuring.

Remind students the in the beginning of the class they do a prediction about the thickness of the small, medium, and long sample. Students should have actually predicted the the longest cylinder has the lowest density, the shortest cylinder has actually the greatest density, and also the center is somewhere in between.

Ask students:

Was her prediction about the thickness of these three samples correct? have actually students watch at their chart with the values for mass, volume, and also density because that each cylinder. Have actually them look because that a relationship in between the volume and the density. Students need to realize that the shortest cylinder has the greatest density and also the longest cylinder has actually the lowest density. Is it fair to say the if 2 samples have actually the very same mass that the one v the bigger volume will have a lower density? Yes.Why?Because the samples have actually the same mass, their volumes will give you an idea around their densities according to the equation D = m/v. If a larger number because that volume is in the denominator, the thickness will be lower. Is it fair to say the the one with the smaller volume will have a higher density? Yes.Why?If a smaller number for volume is in the denominator, the thickness will be higher.