Key Concepts

Just favor solids, liquids also have their very own characteristic density.The volume the a liquid deserve to be measured straight with a graduated cylinder.The molecules of different liquids have various size and mass.The mass and size the the molecule in a liquid and also how very closely they room packed together recognize the density of the liquid.Just choose a solid, the density of a liquid equates to the mass of the liquid split by that volume; D = m/v.The density of water is 1 gram per cubic centimeter.The thickness of a substance is the same regardless the the dimension of the sample.

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Summary

Students measure the volume and mass that water to identify its density. Climate they measure the fixed of various volumes the water and discover that the thickness is constantly the same. Students do a graph that the relationship in between the volume and also the mass of water.

Objective

Students will be able to measure the volume and also mass that water and calculate that density. College student will have the ability to explain the since any volume of water always has the exact same density, in ~ a given temperature, that density is a characteristic residential property of water.

Evaluation

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

Safety

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

Materials for Each Group

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

Materials because that the Demonstration

WaterTwo similar buckets or huge containers
Engage

Do a demonstrate to introduce the idea the water has density.

Materials

WaterTwo the same buckets or huge containers

Teacher preparation

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

Procedure

Select a student to background both buckets of water. Explore

Discuss with students just how to uncover the volume and also mass that water.

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

Ask students:

What two things do you require to recognize in stimulate to discover the thickness of water?Students have to realize that they require both the volume and mass the a sample the water to uncover its density. How have the right to you measure up a volume the water? suggest that students use 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 fixed of water?Suggest that students use a balance to measure the fixed in grams. Tell 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. So in bespeak to sweet the water, they need to weigh the container, too. Explain to students that they will have to subtract the mass of one empty graduated cylinder native the fixed of the cylinder and water to gain the fixed of just the water.
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Have students uncover the massive of different volumes the water to display that the density of water walk not count on the size of the sample.

Question to investigate

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

Materials for each group

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

Procedure

Find the fixed of one empty graduated cylinder. Document the massive in grams in the chart on the activity sheet.

Pour 100 mL the water into the i graduated cylinder. Try to be as specific as possible by checking that the meniscus is ideal at the 100-mL mark. Usage a dropper to include or remove small amounts the water.

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Weigh the graduated cylinder v the water in it. Document the fixed in grams. Uncover the massive of just the water by subtracting the fixed of the empty i graduated cylinder. Document the mass of 100 mL the water in the chart. Usage the mass and also volume the the water to calculate density. Document the thickness in g/cm3 in the chart.Pour off water until you have 50 mL the water in the graduated cylinder. If friend accidentally pour out a small too much, add water until you gain as close together you can to 50 mL.

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

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

Expected results

The density of water should be close come 1 g/cm3. This is true for 100, 50, or 25 mL.

Ask students:

Look in ~ your values for thickness in her chart. Walk the thickness of the various volumes that water seem come be about the same? aid students see that most of the different values for thickness are near 1 g/cm3. They might wonder why their values space not all precisely 1 g/cm3. One reason could be inaccuracies in measuring. One more reason is the the thickness of water alters with temperature. Water is most dense at 4 °C and also at that temperature has actually a thickness of 1 g/cm3. In ~ room temperature, around 20–25 °C, the density is about 0.99 g/cm3. What is the thickness of water in g/cm3? college student answers will vary, however their values should mainly be around 1 g/cm3.

Discuss college student observations, data, and graphs.

Ask students:

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

Tell college student that density is a characteristic property of a substance. This method that the density of a substance is the same regardless the the dimension of the sample.

Ask students:

Is thickness a characteristic property of water? just how do you know?Density is a characteristic building of water due to the fact that the thickness of any sample that water (at the same temperature) is constantly the same. The density is 1 g/cm3.Extend

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

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Give student time to calculation the density of every of the three samples attracted on their activity sheet and answer the connected questions.

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Ask students:

The thickness of a liquid is the very same no matter what the dimension of the sample. Can this be true for solids, too? calculate the density of every of the 3 samples to discover out.Yes. The density of a solid substance is the exact same no issue how large or tiny the sample. Sample A has actually 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 thickness of Sample B?If students perform not know what the mass is, tell them the it is half the massive of Sample A. Because Sample A was 200 g, Sample B is one half the volume and therefore one half the massive (100 g). D = m/vD = 100g/50 cm3D = 2 g/cm3If you cut Sample B in half you would have actually Sample C. What is the thickness of Sample C? D = m/vD = 50g/25 cm3D = 2 g/cm3