Key ConceptsJust prefer 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 various size and also mass.The mass and also size that the molecules in a liquid and also how very closely they space packed together identify the thickness of the liquid.Just like a solid, the density of a liquid amounts to the mass of the liquid split by its volume; D = m/v.The density of water is 1 gram per cubic centimeter.The thickness of a problem is the exact same regardless the the dimension of the sample.
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Students measure the volume and mass of water to determine its density. Climate they measure the mass of different volumes the water and discover the the density is constantly the same. Students make a graph the the relationship in between the volume and the massive of water.
Students will be able to measure the volume and also mass of water and also calculate that is density. Students will have the ability to explain the since any kind of volume of water always has the same density, in ~ a offered temperature, that density is a characteristic building of water.
Download the student activity sheet, and also distribute one every student when specified in the activity. The task sheet will serve together the “Evaluate” component of every 5-E class plan.
Make sure you and your student wear properly fitting goggles.
Materials for Each GroupGraduated cylinder, 100 mlWaterBalance that measures in grams (able to measure over 100 g)Dropper
Materials for the DemonstrationWaterTwo the same buckets or large containers
Do a demonstration to present the idea the water has actually density.
MaterialsWaterTwo identical buckets or huge containers
Half-fill one bucket and include only around 1 cup the water to the other.
ProcedureSelect a student to elevator both buckets the water. Explore
Discuss through students how to discover the volume and also mass the water.
Tell students the they are going to try to discover the thickness of water.
Ask students:What two things carry out you require to recognize in order to uncover the thickness of water?Students have to realize the they require both the volume and mass of a sample of water to uncover its density. How deserve to you measure a volume of water? indicate that students usage a i graduated cylinder to measure volume in milliliters. Remind students that each milliliter amounts to 1 cm3.
Have students discover the fixed of various volumes that water to show that the density of water walk not count on the size of the sample.
Question come investigate
Do different amounts of water have the exact same density?
Materials because that each groupGraduated cylinder, 100 mLWaterBalance that procedures in grams (able to measure over 100 g)Dropper
ProcedureFind the massive of one empty graduated cylinder. Record the fixed in grams in the chart on the activity sheet.
Pour 100 mL of water right into the graduated cylinder. Shot to be as accurate as possible by checking that the meniscus is right at the 100-mL mark. Usage a dropper to add or remove tiny amounts that water.
Find the massive of 50 mL of water. Record the fixed in the activity sheet. Calculate and record the density.
The thickness of water need to be close to 1 g/cm3. This is true for 100, 50, or 25 mL.
Ask students:Look at your values for density in your chart. Does the density of the different volumes of water seem come be about the same? aid students watch that most of the different values for density are close to 1 g/cm3. They may wonder why their values room not all exactly 1 g/cm3. One reason might be inaccuracies in measuring. An additional reason is that the thickness of water alters with temperature. Water is most thick at 4 °C and 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? college student answers will certainly vary, however their worths should largely be roughly 1 g/cm3.
Discuss student observations, data, and graphs.
Ask students:Use her graph to uncover the mass of 40 mL the water. What is the density of this volume that water?The fixed of 40 mL of water is 40 grams. Due to the fact that D = m/v and also mL = cm3, the density of water is 1 g/cm3.Choose a volume in between 1 and 100 mL. Use your graph to find the mass. What is the density of this volume that water? whether students sweet 100, 50, 25 mL or any type of other amount, the density of water will constantly be 1 g/cm3.
Tell college student that thickness is a characteristic building of a substance. This way that the density of a problem is the exact same regardless that the size of the sample.
Ask students:Is thickness a characteristic residential property of water? how do girlfriend know?Density is a characteristic building of water because the density of any kind of sample the water (at the very same temperature) is always the same. The thickness is 1 g/cm3.Extend
Have students take into consideration whether the thickness of a huge piece of a solid substance is the exact same as the thickness of a smaller piece.
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Give students time to calculation the thickness of every of the three samples drawn on their activity sheet and answer the connected questions.
Ask students:The thickness of a fluid is the exact same no issue what the dimension of the sample. Might this be true because that solids, too? calculate the density of each of the three samples to find out.Yes. The thickness of a solid problem is the same no matter how large or small the sample. Sample A has 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, girlfriend would have actually Sample B. What is the density of Sample B?If students do not understand what the massive is, call them the it is fifty percent the massive of Sample A. Because Sample A was 200 g, Sample B is one half 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 half you would have actually Sample C. What is the density of Sample C? D = m/vD = 50g/25 cm3D = 2 g/cm3