Key ConceptsJust choose solids, liquids also have their own characteristic density.The volume the a liquid can be measured directly with a i graduated cylinder.The molecule of different liquids have different size and mass.The mass and also size of the molecules in a liquid and also how very closely they room packed together determine the thickness of the liquid.Just like a solid, the thickness of a liquid equates to the massive of the liquid divided by that is volume; D = m/v.The density of water is 1 gram every cubic centimeter.The density of a problem is the exact same regardless the the dimension of the sample.
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Students measure the volume and mass the water to identify its density. Climate they measure up the fixed of different volumes the water and discover that the density is always the same. Students do a graph that the relationship between the volume and also the massive of water.
Students will have the ability to measure the volume and mass of water and also calculate the density. Students will have the ability to explain the since any volume that water always has the exact same density, in ~ a offered temperature, that density is a characteristic residential or commercial property of water.
Download the student activity sheet, and also distribute one per student as soon as specified in the activity. The activity sheet will serve together the “Evaluate” ingredient of each 5-E lesson plan.
Make certain you and also your students wear effectively fitting goggles.
Materials for Each GroupGraduated cylinder, 100 mlWaterBalance that measures in grams (able to measure over 100 g)Dropper
Materials because that the DemonstrationWaterTwo the same buckets or large containers
Do a demonstrate to present the idea the water has density.
MaterialsWaterTwo similar buckets or big containers
Half-fill one bucket and add only about 1 cup of water come the other.
ProcedureSelect a college student to elevator both buckets that water. Explore
Discuss v students exactly how to uncover the volume and also mass that water.
Tell students the they space going to try to find the density of water.
Ask students:What 2 things perform you require to understand in stimulate to discover the density of water?Students need to realize that they require both the volume and mass that a sample that water to uncover its density. How have the right to you measure up a volume the water? suggest that students usage a graduated cylinder to measure volume in milliliters. Repeat students the each milliliter amounts to 1 cm3.
Have students uncover the fixed of various volumes of water to present that the thickness of water go not depend on the size of the sample.
Question to investigate
Do different amounts of water have actually the very same density?
Materials because that each groupGraduated cylinder, 100 mLWaterBalance that steps in grams (able to measure up over 100 g)Dropper
ProcedureFind the massive of one empty i graduated cylinder. Document the fixed in grams in the chart 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 tiny amounts the water.
Find the massive of 50 mL of water. Document the mass in the task sheet. Calculate and also record the density.
The thickness of water have to be close to 1 g/cm3. This is true because that 100, 50, or 25 mL.
Ask students:Look at your worths for density in her chart. Walk the density of the different volumes that water seem come be about the same? assist students view that many of the different values for thickness are close to 1 g/cm3. They might wonder why their values space not all specifically 1 g/cm3. One reason might be inaccuracies in measuring. Another reason is the the thickness of water transforms with temperature. Water is most thick at 4 °C and at that temperature has a thickness of 1 g/cm3. In ~ room temperature, around 20–25 °C, the density is around 0.99 g/cm3. What is the density of water in g/cm3? students answers will certainly vary, yet their worths should mainly be around 1 g/cm3.
Discuss student observations, data, and also graphs.
Ask students:Use your graph to discover the massive of 40 mL of water. What is the density of this volume of water?The mass of 40 mL the water is 40 grams. Because D = m/v and also mL = cm3, the density of water is 1 g/cm3.Choose a volume between 1 and also 100 mL. Usage your graph to discover the mass. What is the density of this volume that water? even if it is 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 or commercial property of a substance. This means that the thickness of a substance is the exact same regardless the the size of the sample.
Ask students:Is thickness a characteristic building of water? just how do you know?Density is a characteristic residential property of water because the density of any type of sample of water (at the exact same temperature) is always the same. The thickness is 1 g/cm3.Extend
Have students think about whether the thickness of a big piece that a solid substance is the same as the thickness of a smaller piece.
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Give student time to calculate the thickness of every of the 3 samples attracted on their task sheet and answer the connected questions.
Ask students:The density of a fluid is the very same no matter what the size of the sample. Might this be true for solids, too? calculation the density of every of the 3 samples to find out.Yes. The thickness of a solid substance is the same no matter how huge or tiny the sample. Sample A has actually a mass of 200 g. What is the thickness of Sample A? D = m/vD = 200g/100cm3D = 2 g/cm3If you reduced Sample A in fifty percent and looked at just one half, you would have actually Sample B. What is the density of Sample B?If students do not understand what the mass is, phone call them that it is half 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 reduced Sample B in fifty percent you would have actually Sample C. What is the density of Sample C? D = m/vD = 50g/25 cm3D = 2 g/cm3