Key Concepts

Just prefer solids, liquids also have their own characteristic density.The volume the a liquid can be measured straight with a i graduated cylinder.The molecules of various liquids have various size and also mass.The mass and also size the the molecule in a liquid and how carefully they room packed together determine the thickness of the liquid.Just prefer a solid, the density of a liquid equates to the fixed of the liquid split by its volume; D = m/v.The thickness of water is 1 gram every cubic centimeter.The density of a problem is the same regardless the the dimension of the sample.

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Summary

Students measure up the volume and mass that water to recognize its density. Then they measure up the mass of various volumes the water and discover that the thickness is always the same. Students do a graph of the relationship between the volume and the massive of water.

Objective

Students will have the ability to measure the volume and mass of water and calculate the density. Student will have the ability to explain the since any kind of volume that water always has the very same density, in ~ a offered temperature, that density is a characteristic building of water.

Evaluation

Download the student task sheet, and also distribute one per student when specified in the activity. The activity sheet will certainly serve as the “Evaluate” component of every 5-E lesson plan.

Safety

Make certain you and also your college student wear properly fitting goggles.

Materials for Each Group

Graduated cylinder, 100 mlWaterBalance that procedures in grams (able to measure over 100 g)Dropper

Materials for the Demonstration

WaterTwo similar buckets or large containers
Engage

Do a demonstration to present the idea the water has actually density.

Materials

WaterTwo similar buckets or large containers

Teacher preparation

Half-fill one bucket and add only around 1 cup the water to the other.

Procedure

Select a college student to elevator both buckets that water. Explore

Discuss through students how to uncover the volume and mass the water.

Tell students the they room going to shot to uncover the thickness of water.

Ask students:

What 2 things perform you need to recognize in bespeak to find the density of water?Students have to realize that they need both the volume and also mass that a sample of water to find its density. How have the right to you measure a volume the water? imply that students usage a graduated cylinder to measure up volume in milliliters. Remind students the each milliliter amounts to 1 cm3.
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How have the right to you measure up the massive of water?Suggest that students usage a balance to measure up the mass in grams. Tell students the they can discover mass by weighing the water. However, due to the fact that water is a liquid, it demands to be in some sort of container. So in bespeak to sweet the water, they have to weigh the container, too. Explain to students the they will need to subtract the mass of an empty graduated cylinder from the mass of the cylinder and also water to acquire the mass of simply the water.
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Have students discover the fixed of different volumes of water to present that the density of water go not count on the size of the sample.

Question come investigate

Do different quantities of water have the exact same density?

Materials for each group

Graduated cylinder, 100 mLWaterBalance that procedures in grams (able to measure over 100 g)Dropper

Procedure

Find the massive of one empty i graduated cylinder. Record the massive in grams in the chart on the task sheet.

Pour 100 mL that water right into the i graduated cylinder. Try to it is in as precise as possible by checking the the meniscus is ideal at the 100-mL mark. Usage a dropper to include or remove little amounts of water.

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Weigh the i graduated cylinder with the water in it. Document the fixed in grams. Find the mass of just the water by individually the mass of the empty i graduated cylinder. Record the mass of 100 mL of water in the chart. Usage the mass and volume that the water to calculate density. Record the thickness in g/cm3 in the chart.Pour turn off water till you have actually 50 mL that water in the i graduated cylinder. If girlfriend accidentally pour out a little too much, include water till you obtain as close together you deserve to to 50 mL.

Find the mass of 50 mL that water. Record the fixed in the activity sheet. Calculate and record the density.

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Next, pour off water till you have 25 mL the water in the graduated cylinder. Discover the fixed of 25 mL of water and also record that in the chart. Calculate and record the density.Table 1. Recognize the thickness of different volumes that water.Volume the water100 mililiters50 mililiters25 mililitersMass of i graduated cylinder + water (g)Mass of empty i graduated cylinder (g)Mass that water (g)Density the water (g/cm3)

Expected results

The thickness of water must be close to 1 g/cm3. This is true for 100, 50, or 25 mL.

Ask students:

Look in ~ your values for thickness in her chart. Does the thickness of the various volumes of water seem to be about the same? assist students check out that many of the various values for density are close to 1 g/cm3. They may wonder why their values are not all exactly 1 g/cm3. One reason might be inaccuracies in measuring. Another reason is the the thickness of water alters with temperature. Water is most dense at 4 °C and also at the temperature has a density of 1 g/cm3. In ~ room temperature, roughly 20–25 °C, the density is about 0.99 g/cm3. What is the thickness of water in g/cm3? college student answers will certainly vary, but their values should mainly be approximately 1 g/cm3.

Discuss student observations, data, and also graphs.

Ask students:

Use her graph to discover the fixed of 40 mL that water. What is the thickness of this volume that water?The massive of 40 mL that water is 40 grams. Due to the fact that D = m/v and mL = cm3, the thickness of water is 1 g/cm3.Choose a volume in between 1 and 100 mL. Usage your graph to discover the mass. What is the thickness of this volume that water? whether students sweet 100, 50, 25 mL or any kind of other amount, the density of water will constantly be 1 g/cm3.

Tell students that thickness is a characteristic home of a substance. This means that the density of a substance is the exact same regardless that the size of the sample.

Ask students:

Is density a characteristic residential or commercial property of water? how do you know?Density is a characteristic home of water since the density of any sample of water (at the very same temperature) is always the same. The density is 1 g/cm3.Extend

Have students think about whether the density of a large piece that a solid substance is the same as the thickness of a smaller sized piece.

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Give student time to calculation the density of every of the three samples drawn on their task sheet and also answer the related questions.

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Ask students:

The thickness of a fluid is the exact same no issue what the dimension of the sample. Might this it is in true for solids, too? calculation the density of each of the 3 samples to uncover out.Yes. The density of a solid substance is the same no issue how large or small the sample. Sample A has a fixed of 200 g. What is the thickness of Sample A? D = m/vD = 200g/100cm3D = 2 g/cm3If you cut Sample A in fifty percent and looked at only one half, you would have actually Sample B. What is the thickness of Sample B?If students do not recognize what the fixed is, call them the it is half the massive of Sample A. Since Sample A was 200 g, Sample B is one fifty percent the volume and also therefore one half the massive (100 g). D = m/vD = 100g/50 cm3D = 2 g/cm3If you cut Sample B in fifty percent you would have actually Sample C. What is the density of Sample C? D = m/vD = 50g/25 cm3D = 2 g/cm3