### Key Concepts

A submerged object dislocations a volume of liquid equal to the volume of the object.One milliliter (1 mL) of water has actually a volume of 1 cubic centimeter (1cm3).Different atoms have different sizes and masses.Atoms on the periodic table are arranged in order according to the number of prolots in the nucleus.Even though an atom might be smaller sized than another atom, it can have even more mass.The mass of atoms, their dimension, and how they are arranged recognize the thickness of a substance.Density amounts to the mass of the object separated by its volume; D = m/v.Objects with the very same mass however different volume have different densities.You are watching: Why is water displacement more accurate than measuring

### Summary

Students usage the water displacement strategy to uncover the volume of various rods that all have actually the very same mass. They calculate the thickness of each rod, and usage the characteristic density of each product to recognize all 5 rods. Then students think about the connection in between the mass, size, and setup of atoms to define why various rods have different densities. Students will be briefly introduced to the periodic table.

### Objective

Students will be able to define that products have characteristic densities bereason of the various mass, dimension, and arrangement of their atoms. Students will certainly be able to usage the volume displacement approach to discover the volume of an item.

### Evaluation

Downfill the student task sheet, and also distribute one per student once mentioned in the activity. The activity sheet will certainly serve as the “Evaluate” component of each 5-E leschild arrangement.

### Safety

Make certain you and also your students wear correctly fitting goggles.

### Materials for Each Group

Set of 5 various rods that all have the very same massGraduated cylinder, 100 mLWater in a cupCalculator### Notes around the materials:

For this lesboy you will certainly need a set of five solid rods, each with the same mass, same diameter, but a different volume. Each rod is made of a different material. There are a number of versions of these rods available from different companies. This activity uses the Equal Mass Kit from Flinn Scientific (Product #AP4636) however deserve to be adapted to any collection of equal mass rods. Since tbelow are only five samples in the Equal Mass kit, you may require two kits so that each group have the right to work with a sample.

This chart will help you identify each rod. Do not disclose this indevelopment to the students. They will uncover the identification of each rod and also the inverse connection in between the thickness and the length of each rod later on in this lesson.

Table 1. Physical properties for solid cylinder unkowns.SampleMaterialApproximate Density (g/cm3)Relative lengthSmallest metalShiny gray metalDark grayTall off-whiteTallest whiteBrass | 7.5 | shortest |

Aluminum | 3.0 | |

PVC | 1.4 | |

Nylon | 1.1 | |

Polyethylene | 0.94 | longest |

Engage

## Sjust how students 5 rods that have the exact same mass but various volumes.

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

Ask students to make a prediction:

Which rod is the most dense? Leastern dense? In between?Students may reason that because the mass of each rod is the exact same, the volume of each rod have to have something to carry out with its thickness. Some might go so much as to say that the rod via the smallest volume have to have actually the highest possible thickness, bereason the exact same mass is packed into the smallest volume. Or that the rod with the largest volume need to have the lowest thickness, because the exact same mass is spcheck out out over the largest volume.

Tell students that like the cubes in the previous activity, they will need to recognize the volume and mass of each of the samples. They will certainly additionally calculate the thickness of each sample and use this value to number out which material each rod is made of.

## Show an computer animation and show exactly how to meacertain volume using the water displacement method.

Project the animation Water Displacement.

Play the computer animation as you demonstrate the water displacement approach utilizing a cup of water, a graduated cylinder, and a rod, the way students will certainly perform in the task. Use the dark gray plastic sample so that students have the right to see it better.

### Volume

Demonstrate what students will execute by putting water from a cup into a 100-mL graduated cylinder till it reaches a height that will cover the sample. This is the “initial water level.”Tell students that the surchallenge of water in a tube might not be completely flat. Instead, the surface may curve in a shpermit U-form dubbed the meniscus. When measuring, read the line just at the bottom of the meniscus.

Tilt the graduated cylinder and slowly slide the sample into the water. Hold the graduated cylinder upideal. Record the level of the water. Point out that this is the “final water level.”

Tell students that you desire to discover out just how a lot the water level changed. Subtract the initial water level from the final water level to discover the volume of the rod.Volume of sample = final water level − initial water level.

Explore## Have students calculate the thickness of five various rods and use the characteristic building of thickness to effectively recognize them.

Note: The densities for the 3 plastics are similar, so students have to be incredibly careful when measuring their volume using the water displacement method. Also, it is hard to measure the volume of the smallest rod. Give students a hint that it is between 1.5 and 2.0 mL.

### Concern to investigate

Can you use density to recognize all five rods?

### Materials for each group

Set of 5 various rods that all have the exact same massGraduated cylinder, 100 mLWater in a cupCalculator### Teacher preparation

Use a long-term marker to note the five rods with letters A, B, C, D, and also E. Keep track of which letter synchronizes to which sample without letting students recognize. If you are making use of 2 or more sets of rods, be certain to mark each sample of the exact same product through the very same letter. After a group finds the volume of a sample, they have to then pass that sample to an additional team till all teams have discovered the volume of all 5 rods. For the longest sample, which floats, students deserve to use a pencil to gently push the sample just beneath the surface of the water to measure its complete volume.### Procedure

VolumePour sufficient water from your cup into the graduated cylinder to reach a elevation that will cover the sample. Read and document the volume. Slightly tilt the graduated cylinder and carefully place the sample right into the water. Place the graduated cylinder upideal on the table and look at the level of the water. If the sample floats, use a pencil to gently push the height of the sample simply under the surface of the water. Record the number of milliliters for this final water level.Find the amount of water disput by subtracting the initial level of the water from the last level. This volume amounts to the volume of the cylinder in cm3.

Record this volume in the chart on the task sheet.Remove the sample by pouring the water back right into your cup and also taking the sample out of your graduated cylinder.DensityCalculate the thickness making use of the formula D = m/v. Record the thickness in (g/cm3).Trade samples with other groups until you have actually measured the volume and calculated the thickness of all five samples. Table 2. Volume, mass, and thickness for unknowns A–HSampleInitial water level (mL)Final water level (mL)Volume of the rods (cm3)Mass (g)Density (g/cm3)ABCDE15.0 | ||||

15.0 | ||||

15.0 | ||||

15.0 | ||||

15.0 |

Note: The densities students calculate might not be specifically the same as the offered densities in the chart. As students are functioning, examine their worths for volume to be certain that they are utilizing the difference in between the last and also initial water levels, not just the final level.

Table 3. Volume, mass, and also thickness for unknowns A–HMaterialApproximate density (g/cm3)Sample (Letters A–E)BrassAluminumPVCNylonPolyethylene8.8 | |

2.7 | |

1.4 | |

1.2 | |

0.94 |

## Discuss whether students’ values for thickness assistance their predictions from the beginning of the leskid.

Discuss student worths for density for each of the samples. Point out that different teams may have actually different values for thickness, yet that the majority of of the worths are close to the values in the chart.

See more: Reasons Why Does My Cat Want To Go Outside All Of A Sudden, How To Prevent Indoor Cats From Escaping

Ask students:

Each group measured the volume of the exact same samples. What are some factors that teams could have different values for density?Students have to realize that tiny inaccuracies in measuring volume deserve to account for differences in density values. Another reason is that the graduated cylinder, itself, is not perfect. So tright here is constantly some uncertainty in measuring.Remind students that in the start of the leschild they made a prediction about the thickness of the tiny, tool, and also long sample. Students must have predicted that the longest cylinder has actually the lowest thickness, the shortest cylinder has the highest thickness, and the middle is somewright here in between.

Ask students:

Was your prediction about the density of these three samples correct? Have students look at their chart with the values for mass, volume, and density for each cylinder. Have them look for a connection in between the volume and the density. Students should realize that the shortest cylinder has actually the best density and the longest cylinder has the lowest thickness. Is it fair to say that if 2 samples have the very same mass that the one through the bigger volume will certainly have actually a reduced density? Yes.Why?Since the samples have actually the very same mass, their quantities will certainly give you an principle around their densities according to the equation D = m/v. If a larger number for volume is in the denominator, the density will be lower. Is it fair to say that the one via the smaller sized volume will have a higher density? Yes.Why?If a smaller sized number for volume is in the denominator, the density will certainly be greater.