Key Concepts

Just favor solids, liquids also have their own characteristic density.The volume that 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 molecules in a liquid and how carefully they space packed together determine the thickness of the liquid.Just prefer a solid, the thickness of a liquid equates to the mass of the liquid split by its volume; D = m/v.The density of water is 1 gram every cubic centimeter.The thickness of a substance is the exact same regardless of the dimension of the sample.

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Summary

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

Objective

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

Evaluation

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

Safety

Make sure you and also your student wear correctly fitting goggles.

Materials because that Each Group

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

Materials because that the Demonstration

WaterTwo the same buckets or large containers
Engage

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

Materials

WaterTwo similar buckets or large containers

Teacher preparation

Half-fill one bucket and include only about 1 cup the water come the other.

Procedure

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

Discuss with students how to find the volume and also mass the water.

Tell students that they space going to try to discover the density of water.

Ask students:

What two things do you require to understand in bespeak to uncover the thickness of water?Students should realize that they require both the volume and also mass that a sample that water to find its density. How have the right to you measure up a volume the water? suggest that students usage a i graduated cylinder to measure volume in milliliters. Remind students the each milliliter equals 1 cm3.
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How can you measure up the mass of water?Suggest that students usage a balance to measure the fixed in grams. Tell students that they can find mass by weighing the water. However, since water is a liquid, it demands to it is in in some sort of container. So in stimulate to sweet the water, they have to weigh the container, too. Explain to students that they will need to subtract the mass of one empty i graduated cylinder indigenous the mass of the cylinder and water to acquire the fixed of just the water.
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Have students uncover the massive of various volumes the water to present that the thickness of water does not rely on the dimension of the sample.

Question to investigate

Do different quantities of water have the exact same density?

Materials for each group

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

Procedure

Find the mass of an empty i graduated cylinder. Record the fixed in grams in the graph on the activity sheet.

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

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Weigh the graduated cylinder v the water in it. Record the fixed in grams. Find the fixed of just the water by individually the massive of the empty i graduated cylinder. Record the mass of 100 mL the water in the chart. Usage the mass and also volume of the water to calculate density. Record the density in g/cm3 in the chart.Pour off water until you have actually 50 mL that water in the graduated cylinder. If friend accidentally pour the end a small too much, include water until you gain as close as you have the right to to 50 mL.

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

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Next, pour off water until you have 25 mL that water in the graduated cylinder. Uncover the fixed of 25 mL that water and record it in the chart. Calculate and also record the density.Table 1. Recognize the thickness of various volumes of 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 density 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 different volumes the water seem to be about the same? assist students watch that most of the different values for thickness are close to 1 g/cm3. They might wonder why your values space not all specifically 1 g/cm3. One reason might be inaccuracies in measuring. Another reason is that the density of water transforms with temperature. Water is most thick at 4 °C and also at the temperature has a density of 1 g/cm3. In ~ room temperature, approximately 20–25 °C, the density is around 0.99 g/cm3. What is the density of water in g/cm3? college student answers will certainly vary, but their worths should greatly be approximately 1 g/cm3.

Discuss college student observations, data, and also graphs.

Ask students:

Use your graph to find the fixed of 40 mL that water. What is the thickness of this volume that water?The fixed 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 in between 1 and also 100 mL. Use your graph to uncover the mass. What is the thickness of this volume the water? whether students sweet 100, 50, 25 mL or any kind of other amount, the density of water will always be 1 g/cm3.

Tell student that density is a characteristic residential property of a substance. This way that the density of a problem is the very same regardless of the dimension of the sample.

Ask students:

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

Have students consider whether the thickness of a large piece of a solid substance is the same as the thickness of a smaller sized piece.

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Give college student time to calculation the thickness of every of the 3 samples attracted on their task sheet and answer the associated questions.

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Ask students:

The thickness of a fluid is the same no issue what the dimension of the sample. Can this it is in true because that solids, too? calculation the density of each of the 3 samples to uncover out.Yes. The thickness of a solid substance is the same no issue how big or little the sample. Sample A has actually a massive of 200 g. What is the density of Sample A? D = m/vD = 200g/100cm3D = 2 g/cm3If you reduced Sample A in half and looked at only one half, girlfriend would have Sample B. What is the density of Sample B?If students execute not recognize what the fixed is, tell them the it is half the fixed of Sample A. Since Sample A was 200 g, Sample B is one half the volume and therefore one fifty percent 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 density of Sample C? D = m/vD = 50g/25 cm3D = 2 g/cm3