Key Concepts

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

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Summary

Students measure the volume and also mass that water to recognize its density. Climate they measure up the mass of different volumes the water and also discover that the thickness is constantly the same. Students do a graph that the relationship between the volume and the mass of water.

Objective

Students will be able to measure the volume and also mass that water and calculate the density. College student will be able to explain the since any volume that water constantly has the exact same density, in ~ a offered temperature, that thickness is a characteristic residential or commercial property of water.

Evaluation

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

Safety

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

Materials because that Each Group

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

Materials for the Demonstration

WaterTwo the same buckets or huge containers
Engage

Do a demonstration to introduce the idea that water has density.

Materials

WaterTwo identical buckets or huge containers

Teacher preparation

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

Procedure

Select a student to background both buckets that water. Explore

Discuss with students exactly how to uncover the volume and mass the water.

Tell students the they are going to shot to find the thickness of water.

Ask students:

What 2 things do you require to understand in bespeak to discover the thickness of water?Students must realize the they require both the volume and mass that a sample of water to uncover its density. How can you measure up a volume that water? indicate that students use a i graduated cylinder to measure up volume in milliliters. Repeat students the each milliliter equals 1 cm3.
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How have the right to you measure up the mass of water?Suggest that students usage a balance to measure the massive in grams. Call students the they can uncover mass by weighing the water. However, due to the fact that water is a liquid, it requirements to be in some sort of container. Therefore in bespeak to weigh the water, they need to weigh the container, too. Explain to students the they will have to subtract the massive of an empty graduated cylinder native the fixed of the cylinder and water to acquire the mass of simply the water.
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Have students discover the massive of various volumes of water to show that the density of water walk not rely on the dimension of the sample.

Question to investigate

Do different quantities of water have actually the very same density?

Materials because that each group

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

Procedure

Find the massive of one empty graduated cylinder. Document the mass in grams in the chart on the task sheet.

Pour 100 mL of water into the graduated cylinder. Shot to it is in as accurate as feasible by checking the the meniscus is right at the 100-mL mark. Use a dropper to add or remove tiny amounts that water.

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Weigh the i graduated cylinder through the water in it. Document the mass in grams. Find the massive of only the water by subtracting the mass of the empty i graduated cylinder. Record the fixed of 100 mL of water in the chart. Use the mass and volume that the water to calculate density. Record the thickness in g/cm3 in the chart.Pour turn off water until you have 50 mL that water in the i graduated cylinder. If friend accidentally pour out a little too much, add water till you get as close together you have the right to to 50 mL.

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

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

Expected results

The thickness of water have to be close come 1 g/cm3. This is true because that 100, 50, or 25 mL.

Ask students:

Look in ~ your worths for density in your chart. Does the thickness of the different volumes that water seem to be around the same? aid students check out that most of the various values for thickness are near 1 g/cm3. They may wonder why your values room not all exactly 1 g/cm3. One reason could be inaccuracies in measuring. An additional reason is the the density of water changes with temperature. Water is most thick at 4 °C and also at the temperature has actually a density of 1 g/cm3. In ~ room temperature, around 20–25 °C, the thickness is around 0.99 g/cm3. What is the density of water in g/cm3? student answers will certainly vary, but their values should largely be around 1 g/cm3.

Discuss student observations, data, and also graphs.

Ask students:

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

Tell students that thickness is a characteristic building of a substance. This method that the thickness of a problem is the very same regardless of the dimension of the sample.

Ask students:

Is thickness a characteristic home of water? exactly how do you know?Density is a characteristic building of water because the thickness of any sample that water (at the same temperature) is constantly the same. The thickness is 1 g/cm3.Extend

Have students consider whether the thickness of a big piece of a solid problem is the very same as the thickness of a smaller piece.

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Give student time to calculation the density of each of the 3 samples attracted on their task sheet and also answer the associated questions.

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Ask students:

The thickness of a liquid is the exact same no issue what the dimension of the sample. Might this it is in true for solids, too? calculate the density of every of the three samples to find out.Yes. The thickness of a solid problem is the exact same no issue how large or tiny 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, girlfriend would have actually Sample B. What is the density of Sample B?If students do not know what the mass is, phone call them that it is half the fixed of Sample A. Since Sample A was 200 g, Sample B is one fifty percent the volume and therefore one fifty percent the massive (100 g). D = m/vD = 100g/50 cm3D = 2 g/cm3If you reduced Sample B in fifty percent you would have Sample C. What is the thickness of Sample C? D = m/vD = 50g/25 cm3D = 2 g/cm3