Key Concepts

Just prefer solids, liquids likewise have their own characteristic density.The volume the a liquid deserve to be measured directly with a graduated cylinder.The molecules of various liquids have different size and also mass.The mass and also size of the molecules in a liquid and how very closely they room packed together determine the thickness of the liquid.Just favor a solid, the thickness of a liquid equals the mass of the liquid separated by its volume; D = m/v.The thickness of water is 1 gram per cubic centimeter.The density of a problem is the exact same regardless that the size of the sample.

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Summary

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

Objective

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

Evaluation

Download the student activity sheet, and also distribute one per student once specified in the activity. The activity sheet will serve as the “Evaluate” ingredient of every 5-E class plan.

Safety

Make sure you and your college student wear appropriately fitting goggles.

Materials for Each Group

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

Materials for the Demonstration

WaterTwo similar buckets or huge containers
Engage

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

Materials

WaterTwo similar buckets or big containers

Teacher preparation

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

Procedure

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

Discuss with students just how to discover the volume and mass the water.

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

Ask students:

What 2 things do you need to know in bespeak to find the thickness of water?Students have to realize that they require both the volume and also mass that a sample of water to discover its density. How deserve to you measure a volume that water? imply that students use a i graduated cylinder to measure volume in milliliters. Remind students that each milliliter equals 1 cm3.
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How can you measure up the mass of water?Suggest that students use a balance to measure up the fixed in grams. Phone call students that they can uncover mass by weighing the water. However, because water is a liquid, it demands to it is in in some kind of container. For this reason in bespeak to sweet the water, they have to weigh the container, too. Define to students the they will need to subtract the massive of an empty i graduated cylinder indigenous the fixed of the cylinder and also water to gain the mass of simply the water.
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Have students find the fixed of different volumes that water to display that the thickness of water walk not count on the size of the sample.

Question to investigate

Do different quantities of water have actually the same density?

Materials for each group

Graduated cylinder, 100 mLWaterBalance that actions in grams (able to measure up 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 the water into the i graduated cylinder. Shot to be as accurate as feasible by checking that the meniscus is ideal at the 100-mL mark. Use a dropper to add or remove little amounts of water.

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Weigh the i graduated cylinder through the water in it. Record the massive in grams. Uncover the fixed of just the water by individually the fixed of the empty i graduated cylinder. Record the fixed of 100 mL the water in the chart. Use the mass and volume the the water to calculation density. Document the thickness in g/cm3 in the chart.Pour off water until you have actually 50 mL the water in the graduated cylinder. If girlfriend accidentally pour out a tiny too much, include water till you obtain as close as you have the right to to 50 mL.

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

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

Expected results

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

Ask students:

Look at your worths for density in your chart. Does the density of the different volumes that water seem to be about the same? help students view that many 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 could be inaccuracies in measuring. Another reason is that the density of water changes with temperature. Water is most dense at 4 °C and at that 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? student answers will certainly vary, yet their worths should largely be around 1 g/cm3.

Discuss student observations, data, and graphs.

Ask students:

Use your graph to discover the massive of 40 mL the water. What is the thickness of this volume that water?The fixed of 40 mL the 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 100 mL. Usage your graph to uncover the mass. What is the density of this volume the water? whether students sweet 100, 50, 25 mL or any other amount, the density of water will constantly be 1 g/cm3.

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

Ask students:

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

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

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

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Ask students:

The density of a fluid is the very same no issue what the dimension of the sample. Could this it is in true because that solids, too? calculation the thickness of each of the three samples to find out.Yes. The thickness of a solid substance is the very same no issue how huge or little the sample. Sample A has actually a fixed 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 just one half, you would have Sample B. What is the density of Sample B?If students do not recognize what the fixed is, call them that it is half the mass of Sample A. Because Sample A was 200 g, Sample B is one half the volume and therefore one half the fixed (100 g). D = m/vD = 100g/50 cm3D = 2 g/cm3If you reduced Sample B in half you would have Sample C. What is the thickness of Sample C? D = m/vD = 50g/25 cm3D = 2 g/cm3