Key ConceptsJust prefer solids, liquids also have their very own characteristic density.The volume of a liquid can be measured straight with a i graduated cylinder.The molecules of various liquids have various size and mass.The mass and size of the molecules in a liquid and also how closely they are packed together determine the density of the liquid.Just choose a solid, the thickness of a liquid equates to the massive of the liquid split by the volume; D = m/v.The density of water is 1 gram every cubic centimeter.The density of a problem is the same regardless of the dimension of the sample.
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Students measure up the volume and also mass that water to identify its density. Climate they measure the mass of various volumes the water and also discover that the density is constantly the same. Students make a graph that the relationship in between the volume and the mass of water.
Students will have the ability to measure the volume and mass the water and calculate that is density. Student will be able to explain the since any type of volume that water always has the exact same density, in ~ a given temperature, that density is a characteristic building of water.
Download the student task sheet, and distribute one per student once specified in the activity. The task sheet will certainly serve together the “Evaluate” component of each 5-E great plan.
Make sure you and your students wear appropriately fitting goggles.
Materials for Each GroupGraduated cylinder, 100 mlWaterBalance that procedures in grams (able to measure over 100 g)Dropper
Materials because that the DemonstrationWaterTwo similar buckets or huge containers
Do a show to present the idea that water has actually density.
MaterialsWaterTwo identical buckets or huge containers
Half-fill one bucket and add only about 1 cup the water come the other.
ProcedureSelect a student to lift both buckets the water. Explore
Discuss with students just how to discover the volume and also mass of water.
Tell students the they are going to shot to find the density of water.
Ask students:What 2 things execute you require to understand in stimulate to uncover the density of water?Students must realize that they need both the volume and also mass the a sample the water to find its density. How can you measure up a volume that water? imply that students use a i graduated cylinder to measure up volume in milliliters. Repeat students that each milliliter amounts to 1 cm3.
Have students find the massive of different volumes that water to present that the thickness of water go not depend on the dimension of the sample.
Question come investigate
Do different amounts of water have actually the exact same density?
Materials for each groupGraduated cylinder, 100 mLWaterBalance that actions in grams (able to measure over 100 g)Dropper
ProcedureFind the massive of an empty graduated cylinder. Record the mass in grams in the graph on the task sheet.
Pour 100 mL that water into the graduated cylinder. Try to it is in as specific as possible by checking that the meniscus is appropriate at the 100-mL mark. Use a dropper to include or remove little amounts the water.
Find the massive of 50 mL of water. Document the massive in the activity sheet. Calculate and also record the density.
The density of water need to be close to 1 g/cm3. This is true because that 100, 50, or 25 mL.
Ask students:Look at your values for density in her chart. Go the density of the different volumes of water seem come be about the same? aid students see that many of the different values for thickness are near 1 g/cm3. They might wonder why their values are not all precisely 1 g/cm3. One reason might be inaccuracies in measuring. Another reason is that the density of water transforms with temperature. Water is most dense at 4 °C and at that temperature has a thickness of 1 g/cm3. At room temperature, roughly 20–25 °C, the thickness is around 0.99 g/cm3. What is the density of water in g/cm3? students answers will certainly vary, but their worths should mostly be about 1 g/cm3.
Discuss student observations, data, and also graphs.
Ask students:Use your graph to find the mass of 40 mL of water. What is the density of this volume of water?The mass of 40 mL of water is 40 grams. Since D = m/v and mL = cm3, the density of water is 1 g/cm3.Choose a volume between 1 and 100 mL. Use your graph to discover the mass. What is the density of this volume of water? even if it is students weigh 100, 50, 25 mL or any other amount, the thickness of water will constantly be 1 g/cm3.
Tell students that density is a characteristic residential or commercial property of a substance. This method that the thickness of a problem is the exact same regardless the the dimension of the sample.
Ask students:Is density a characteristic building of water? just how do friend know?Density is a characteristic building of water since the thickness of any sample that water (at the very same temperature) is constantly the same. The density is 1 g/cm3.Extend
Have students consider whether the density of a big piece of a solid substance is the very same as the density of a smaller piece.
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Give college student time to calculate the density of each of the three samples attracted on their activity sheet and also answer the associated questions.
Ask students:The thickness of a fluid is the exact same no issue what the dimension of the sample. Can this it is in true for 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 matter how large or little 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 reduced Sample A in half and looked at only one half, friend would have actually Sample B. What is the thickness of Sample B?If students perform not understand what the fixed is, tell them that it is fifty percent the fixed of Sample A. Because Sample A to be 200 g, Sample B is one fifty percent the volume and also therefore one fifty percent the mass (100 g). D = m/vD = 100g/50 cm3D = 2 g/cm3If you cut Sample B in fifty percent you would have actually Sample C. What is the thickness of Sample C? D = m/vD = 50g/25 cm3D = 2 g/cm3