Key Concepts

A submerged thing displaces a volume of liquid equal to the volume that the object.One milliliter (1 mL) that water has actually a volume the 1 cubic centimeter (1cm3).Different atoms have different sizes and also masses.Atoms on the regular table room arranged in order follow to the variety of protons in the nucleus.Even though an atom may be smaller than one more atom, it could have more mass.The fixed of atoms, their size, and how they are arranged recognize the density of a substance.Density equates to the fixed of the object divided by its volume; D = m/v.Objects with the exact same mass but different volume have various densities.

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Students use the water displacement method to find the volume of different rods that all have the exact same mass. They calculation the thickness of each rod, and use the characteristic density of each product to identify all five rods. Then students consider the relationship between the mass, size, and arrangement of atom to explain why different rods have various densities. Students will certainly be briefly presented to the periodic table.


Students will have the ability to explain that materials have actually characteristic densities because of the different mass, size, and also arrangement of their atoms. Student will be able to use the volume displacement an approach to find the volume of an object.


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


Make certain you and your student wear properly fitting goggles.

Materials for Each Group

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

Notes around the materials:

For this lesson friend will need a set of 5 solid rods, each v the same mass, same diameter, but a various volume. Each rod is made of a different material. Over there are several versions of this rods easily accessible from various suppliers. This activity uses the equal Mass Kit from Flinn clinical (Product #AP4636) yet can be adjusted to any collection of equal mass rods. Due to the fact that there room only five samples in the equal Mass kit, you may need two kits so that each team can job-related with a sample.

This graph will aid you determine each rod. Execute not reveal this info to the students. They will discover the identity of every rod and the inverse relationship between the density and the size of every rod later on in this lesson.

Table 1. Physics properties for solid cylinder unkowns.SampleMaterialApproximate density (g/cm3)Relative lengthSmallest metalShiny gray metalDark grayTall off-whiteTallest white


Show students five rods that have the exact same mass but different volumes.

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

Ask college student to make a prediction:

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

Students might reason that since the massive of each rod is the same, the volume of every rod must have actually something to perform with that is density. Some may go so far as to say the the rod through the the smallest volume must have the highest density, due to the fact that the exact same mass is packed into the the smallest volume. Or the the rod v the largest volume must have the shortest density, since the exact same mass is spread out out end the biggest volume.

Tell college student that favor the cubes in the ahead activity, they will require to understand the volume and also mass of each of the samples. Lock will additionally calculate the thickness of each sample and use this worth to figure out which product each pole is do of.

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

Project the animation Water Displacement.

Play the animation as you demonstrate the water displacement method using a cup that water, a graduated cylinder, and also a rod, the way students will execute in the activity. Usage the dark gray plastic sample so the students can see the better.


Demonstrate what students will execute by pouring water indigenous a cup right into a 100-mL graduated cylinder till it reaches a height that will cover the sample. This is the “initial water level.”

Tell students the the surface ar of water in a tube may not be fully flat. Instead, the surface may curve in a shallow U-shape referred to as the meniscus. When measuring, review the line simply at the bottom the the meniscus.


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

Tell students that you desire to find out exactly how much the water level changed. Subtract the initial water level indigenous the final water level to discover the volume the the rod.

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


Have students calculate the density of five various rods and also use the characteristic residential or commercial property of thickness to correctly identify them.

Note: The densities because that the three plastics are similar, for this reason students must be an extremely careful when measuring your volume making use of the water displacement method. Also, it is complicated to measure up the volume that the smallest rod. Offer students a hint that it is in between 1.5 and also 2.0 mL.

Question come investigate

Can you use thickness to recognize all 5 rods?

Materials for each group

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

Teacher preparation

Use a permanent marker to note the 5 rods v letters A, B, C, D, and E. Store track of i beg your pardon letter corresponds to i beg your pardon sample there is no letting college student know. If you room using 2 or more sets the rods, be sure to mark each sample the the same material with the exact same letter. ~ a group finds the volume of a sample, they should then pass that sample to an additional group until all groups have discovered the volume of all 5 rods. Because that the longest sample, which floats, students deserve to use a pencil come gently press the sample simply beneath the surface of the water to measure its complete volume.


VolumePour sufficient 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. Slightly tilt the graduated cylinder and carefully ar the sample right into the water. Location the i graduated cylinder upright top top the table and also look in ~ the level that the water. If the sample floats, usage a pencil come gently press the height of the sample simply under the surface ar of the water. Record the variety of milliliters because that this last water level.

Find the amount of water displaced by subtracting the early level the the water native the final level. This volume amounts to the volume the the cylinder in cm3.

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

Note: The densities students calculate may not be specifically the exact same as the provided densities in the chart. Together students room working, inspect their values for volume come be sure that they space using the difference in between the final and also initial water levels, not just the final level.

Table 3. Volume, mass, and also density for unknowns A–HMaterialApproximate density (g/cm3)Sample (Letters A–E)BrassAluminumPVCNylonPolyethylene

Discuss whether students’ values for density support your predictions native the beginning of the lesson.

Discuss student worths for thickness for every of the samples. Suggest out that various groups might have various values because that density, yet that most of the values room close to the values in the chart.

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Ask students:

Each team measured the volume that the same samples. What space some factors that groups could have different values because that density?Students should realize that tiny inaccuracies in measure volume deserve to account for differences in thickness values. One more reason is the the graduated cylinder, itself, is not perfect. So there is constantly some suspicion in measuring.

Remind students that in the beginning of the class they make a prediction around the density of the small, medium, and also long sample. Students should have actually predicted the the longest cylinder has the shortest density, the shortest cylinder has actually the highest possible density, and the middle is somewhere in between.

Ask students:

Was her prediction about the thickness of these 3 samples correct? have actually students watch at their chart v the worths for mass, volume, and density for each cylinder. Have actually them look because that a relationship between the volume and also the density. Students must realize the the shortest cylinder has the biggest density and also the longest cylinder has the lowest density. Is it fair to say the if two samples have the exact same mass the the one v the larger volume will have actually a reduced density? Yes.Why?Because the samples have actually the very same mass, their quantities will offer you one idea about their densities follow to the equation D = m/v. If a larger number because that volume is in the denominator, the density will it is in lower. Is it same to say that the one through the smaller sized 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.