Part I: How Dense Is It? Fundaental Question: What is atter, and how do we identify it? 1. What is the definition of atter? 2. What do you think the ter ass per unit volue eans? 3. Do you think that a part or slice of a substance will have a different density than the whole piece? Explain your ideas about this. 4. How ight you deterine the density of an irregularly shaped object? 1
Part II: Know Your Units! Fundaental Question: How is density easured? Record the length, width, and height of the potato cube, then calculate the volue. olue (c 3 ) Length (c) Width (c) Height (c) = l x w x h 6.6B: Density Using a triple bea balance, deterine the ass of the potato cube. Mass = g Calculate the density of the potato cube below don t forget units in the final answer space. Potato Cube Density D = g c 3 D = Copare the diensions and density of your potato cube with those of two other students. Record the data below (don t forget to include the units): Your cube: Diensions, Mass and Density Potato L W H Mass Density D= Student 1 cube: Student 2 cube: Were the easureents and the density calculations the sae or different for three potato cubes? Do you think the density calculations should be the sae or should they be different? Explain your thinking. 2
Part II: Know Your Units, continued Calculate the Density of a Potato Cube by Displaceent Initial olue of Water L Final olue of Water L Final volue Initial volue = volue of the potato cube in L -- = (final volue) (initial volue) (volue of potato) Since the potato cube is a solid you need to convert the L easureent to cubic gras using the conversion: 1 c 3 = 1 L. What is the volue of your potato cube olue = c 3 What is the ass of your potato cube? Mass = g What is the density of your potato cube when using the displaceent ethod? Mass olue Density D= Questions You have now calculated the density of your potato cube using two different ways of deterining the volue. It is tie to think about your results. 1. Were the results fro the two ethods the sae or were they different? 2. If the calculations were different, which ethod do you think gave you the ore accurate nuber? Why? 3. The density of water is 1.0 g/l. How ight you use the fact that your potato sank to the in the water to discuss the accuracy of your two potato density easureents? (Hint: if an object sinks in water is it ore or less dense than water?) 3
Part III: Coparing the Density of Substances Fundaental Question: How is density easured? 6.6B: Density 1. Carve a potato sculpture and then calculate the density of the potato. 2. Calculate the density of two additional substances provided by your teacher. One ay be obtained by cutting your cube in half. 3. Record your data in the following table: Coparison of Densities Substance olue Mass Density D= Potato Sculpture Substance 1: Substance 2: Questions: 1. Was your potato sculpture s density the sae or different fro your potato cube? Why do you think it was different or the sae? _ 2. Discuss the other two objects you tested and copare their densities to each other and to your potato cube. _ 3. Why do you think that the densities of the other objects are different or the sae copared to the potato cube? 4
Part I: Calculating the Density of a Liquid Fundaental Questions: Can the density of an unknown substance be calculated? Use the table provided below to record your easureents fro the three unknown liquids. Then calculate the density of each liquid aking sure to include the correct units in your answer. Once you have copleted your easureents and density calculations, your teacher will provide you with a table to use to identify the substances. Then answer the questions at the botto of the page. To deterine the ass of each liquid: Mass of Liquid = (ass of liquid & cylinder) (ass of epty cylinder) Mass of Liquid #1 = - = Mass of Liquid #2 = - = Mass of Liquid #3 = - = Using Density to Identify Unknown Substances Beaker # Mass (g) olue (L) Density D= Identity of Substance 1. What easureent, ass or volue, was the sae for all three liquids? 2. What easureent, ass or volue, was different for all three liquids? 3. Look up the densities you calculated on the table provided by your teacher to identify each substances. Record the substance identify in your table. Why are the densities of these three liquids different? Explain. 5
Part I: Calculating the Density of a Liquid, continued 4. If you had used 80 L of these liquids instead of 40 L, would there be a change in the ass? Explain your thinking. 5. If you had used 80 L of these liquids instead of 40 L, would there be a change in the density? Explain your thinking. 6. Describe in your own words the steps you followed to deterine the density of a liquid. Include diagras with your description. Steps to Deterining the Density of a Liquid Steps Diagras, Forulas, etc. 6
Reflections and Conclusions 1. In the space provided below, write the basic forula for density. 2. If you are calculating the density of a solid, what unit of ass and what unit of volue would you use? Mass Unit: olue Unit: 3. If you are calculating the density of a liquid, what unit of ass and what unit of volue would you use? Mass Unit: olue Unit: 4. You have been asked to identify an unknown liquid. The ass of 45 L of the unknown liquid is 36 gras. The densities of four liquids are listed below. What is the identity of the unknown liquid? Circle the correct answer Liquid Water Propyl Alcohol Glycerol Acetic Acid Density 1.00 g/l 0.80 g/l 1.26 g/l 1.05 g/l 7