Key ConceptsJust choose solids, liquids additionally have their very own characteristic density.The volume that a liquid can be measured straight with a graduated cylinder.The molecules of different liquids have various size and also mass.The mass and size the the molecules in a liquid and also how carefully they are packed together determine the thickness of the liquid.Just prefer a solid, the density of a liquid amounts to the mass of the liquid separated by the 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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Students measure the volume and also mass that water to recognize its density. Then they measure up the fixed of various volumes that water and also discover that the thickness is constantly the same. Students do a graph of the relationship in between the volume and the massive of water.
Students will be able to measure the volume and also mass that water and calculate its density. Students will be able to explain that since any volume that water always has the exact same density, in ~ a given temperature, that density is a characteristic property of water.
Download the student task sheet, and also distribute one per student when specified in the activity. The task sheet will certainly serve as the “Evaluate” component of each 5-E great plan.
Make sure you and your student wear appropriately fitting goggles.
Materials for Each GroupGraduated cylinder, 100 mlWaterBalance that actions in grams (able to measure up over 100 g)Dropper
Materials for the DemonstrationWaterTwo identical buckets or big containers
Do a demonstrate to present the idea that water has density.
MaterialsWaterTwo identical buckets or big containers
Half-fill one bucket and include only around 1 cup that water to the other.
ProcedureSelect a student to lift both buckets that water. Explore
Discuss through students just how to discover the volume and also mass the water.
Tell students that they room going to try to find the density of water.
Ask students:What 2 things carry out you need to understand in bespeak to uncover the thickness of water?Students should realize that they need both the volume and also mass of a sample the water to uncover its density. How can you measure a volume that water? imply that students use a graduated cylinder to measure up volume in milliliters. Remind students that each milliliter equates to 1 cm3.
Have students discover the massive of different volumes the water to display that the thickness of water does not rely on the size of the sample.
Question to investigate
Do different amounts of water have the exact same density?
Materials for each groupGraduated cylinder, 100 mLWaterBalance that actions in grams (able to measure up over 100 g)Dropper
ProcedureFind the massive of an empty graduated cylinder. Document the mass in grams in the graph on the activity sheet.
Pour 100 mL of water into the graduated cylinder. Shot to it is in as accurate as possible by checking the the meniscus is ideal at the 100-mL mark. Use a dropper to include or remove little amounts that water.
Find the massive of 50 mL the water. Record the fixed in the task sheet. Calculate and also record the density.
The density of water must be close to 1 g/cm3. This is true because that 100, 50, or 25 mL.
Ask students:Look at your values for thickness in her chart. Does the density of the different volumes that water seem to be around the same? aid students view that most of the various values for density are close to 1 g/cm3. They may wonder why your values space not all precisely 1 g/cm3. One reason could be inaccuracies in measuring. Another reason is the the density of water changes with temperature. Water is most thick at 4 °C and also at the temperature has a thickness of 1 g/cm3. In ~ room temperature, about 20–25 °C, the thickness is about 0.99 g/cm3. What is the density of water in g/cm3? students answers will vary, however their values should mostly be about 1 g/cm3.
Discuss student observations, data, and graphs.
Ask students:Use her graph to discover the massive of 40 mL that water. What is the density of this volume that water?The massive of 40 mL the 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 discover the mass. What is the density of this volume that water? whether students sweet 100, 50, 25 mL or any other amount, the density of water will always be 1 g/cm3.
Tell student that density is a characteristic residential or commercial property of a substance. This way that the thickness of a problem is the same regardless the the dimension of the sample.
Ask students:Is thickness a characteristic home of water? exactly how do girlfriend know?Density is a characteristic home 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 consider whether the density of a large piece of a solid problem is the very same as the thickness of a smaller piece.
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Give students time to calculate the thickness of every of the three samples drawn on their activity sheet and answer the associated questions.
Ask students:The thickness of a fluid is the same no issue what the size of the sample. Could this it is in true for solids, too? calculation the density of every of the 3 samples to uncover out.Yes. The density of a solid problem is the exact same no issue how huge or small the sample. Sample A has a mass 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 thickness of Sample B?If students carry out not understand what the mass is, tell them the it is fifty percent the mass of Sample A. Due to the fact that Sample A to be 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 fifty percent you would have Sample C. What is the density of Sample C? D = m/vD = 50g/25 cm3D = 2 g/cm3