Key Concepts

A submerged thing displaces a volume that liquid same to the volume that the object.One milliliter (1 mL) that water has actually a volume the 1 cubic centimeter (1cm3).Different atoms have various sizes and masses.Atoms top top the regular table are arranged in order follow to the number of protons in the nucleus.Even despite an atom might be smaller sized than one more atom, it can have much more mass.The mass of atoms, your size, and how they room arranged determine the density of a substance.Density amounts to the massive of the object divided by that is volume; D = m/v.Objects with the exact same mass but different volume have different densities.

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Summary

Students usage the water displacement method to uncover the volume of various rods the all have the exact same mass. They calculate the thickness of each rod, and use the characteristic density of each product to identify all five rods. Then students take into consideration the relationship in between the mass, size, and also arrangement of atoms to define why different rods have various densities. Students will certainly be briefly introduced to the periodic table.

Objective

Students will have the ability to explain the materials have actually characteristic densities because of the various mass, size, and arrangement of their atoms. Students will have the ability to use the volume displacement technique to uncover the volume of one object.

Evaluation

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

Safety

Make certain you and your college student wear appropriately fitting goggles.

Materials for Each Group

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

Notes around the materials:

For this lesson girlfriend will require a set of five solid rods, each with the very same mass, same diameter, however a different volume. Every rod is make of a various material. Over there are numerous versions of this rods obtainable from various suppliers. This activity uses the same Mass Kit native Flinn clinical (Product #AP4636) yet can be adapted to any collection of equal mass rods. Due to the fact that there space only 5 samples in the same Mass kit, you may need 2 kits so the each group can job-related with a sample.

This chart will assist you recognize each rod. Carry out not reveal this information to the students. They will uncover the identification of every rod and the station relationship in between the density and also the length of each rod later on in this lesson.

Table 1. Physical properties because that 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 the same mass however different volumes.

Show student the 5 rods and explain that they all have the exact same mass. Then host up the longest, middle-sized, and shortest rods and also remind students the they have the exact same mass.

Ask college student to make a prediction:

Which pole is the many dense? the very least dense? In between?

Students might reason that due to the fact that the massive of every rod is the same, the volume of each rod must have something to carry out with the density. Some may go therefore far regarding say the the rod v the the smallest volume must have the highest possible density, due to the fact that the same mass is packed right into the the smallest volume. Or the the rod through the biggest volume must have the shortest density, due to the fact that the very same mass is spread out end the biggest volume.

Tell students that choose the cubes in the vault activity, they will need to recognize the volume and mass of every of the samples. They will also calculate the thickness of each sample and also use this worth to number out which product each stick is make of.

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

Project the animation Water Displacement.

Play the animation as you show the water displacement technique using a cup of water, a i graduated cylinder, and also a rod, the way students will perform in the activity. Usage the dark gray plastic sample so the students have the right to see the better.

Volume

Demonstrate what college student will carry out by putting water indigenous a cup right into a 100-mL i graduated cylinder until it reaches a elevation 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 might curve in a shallow U-shape called the meniscus. As soon as measuring, review the line simply at the bottom of the meniscus.

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Tilt the graduated cylinder and also slowly on slide the sample right into the water. Host the graduated cylinder upright. Document the level of the water. Allude out the this is the “final water level.”

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Tell students the you want to uncover out exactly how much the water level changed. Subtract the early water level indigenous the final water level to uncover the volume that the rod.

Volume of sample = last water level − early stage water level.

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Explore

Have students calculate the density of five different rods and use the characteristic property of thickness to correctly recognize them.

Note: The densities because that the three plastics space similar, for this reason students must be an extremely careful as soon as measuring your volume utilizing the water displacement method. Also, it is challenging to measure up the volume of the smallest rod. Give students a hint that it is between 1.5 and also 2.0 mL.

Question come investigate

Can friend use density to determine all five rods?

Materials for each group

Set of five different rods the all have the exact same massGraduated cylinder, 100 mLWater in a cupCalculator

Teacher preparation

Use a irreversible marker to mark the five rods with letters A, B, C, D, and E. Save track of i beg your pardon letter coincides to which sample without letting students know. If you space using 2 or more sets of rods, be sure to note each sample that the same material with the same letter. ~ a team finds the volume of a sample, they must then pass the sample to one more group until all teams have found the volume the all five rods. Because that the longest sample, i beg your pardon floats, students can use a pencil to gently press the sample just beneath the surface of the water to measure its full volume.

Procedure

VolumePour enough water from your cup right into the i graduated cylinder to with a elevation that will certainly cover the sample. Read and record the volume. Contempt tilt the graduated cylinder and also carefully ar the sample right into the water. Ar the i graduated cylinder upright top top the table and also look at the level of the water. If the sample floats, usage a pencil to gently press the optimal of the sample just under the surface of the water. Record the number of milliliters because that this final water level.

Find the lot of water displaced by individually the early stage level the the water from the final level. This volume equals the volume that the cylinder in cm3.

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Record this volume in the graph on the task sheet.Remove the sample by putting the water ago into your cup and taking the sample out of your graduated cylinder.DensityCalculate the thickness using the formula D = m/v. Record the density in (g/cm3).Trade samples through other teams until you have actually measured the volume and also calculated the density of all five samples. Table 2. Volume, mass, and density because that unknowns A–HSampleInitial water level (mL)Final water level (mL)Volume the the rods (cm3)Mass (g)Density (g/cm3)ABCDE
15.0
15.0
15.0
15.0
15.0
Identify the samplesCompare the values for density you calculated to the values in the chart. Then create the letter surname for every sample in the chart.

Note: The densities student calculate might not be specifically the same as the given densities in the chart. As students are working, examine their values for volume to be certain that they are using the difference in between the final and also 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 even if it is students’ worths for density support your predictions indigenous the start of the lesson.

Discuss student values for density for every of the samples. Allude out that various groups might have different values because that density, but that many of the values room close to the values in the chart.

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Ask students:

Each group measured the volume that the same samples. What room some factors that groups can have various values for density?Students should realize that little inaccuracies in measuring volume have the right to account for distinctions in thickness values. Another reason is that the graduated cylinder, itself, is no perfect. So over there is constantly some uncertainty in measuring.

Remind students the in the start of the class they do a prediction about the density of the small, medium, and long sample. Student should have actually predicted the the longest cylinder has actually the shortest density, the shortest cylinder has actually the highest density, and the center is what in between.

Ask students:

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