Student Exploration: Density Laboratory

Student Exploration: Density Laboratory NCVPS Chemistry Fall 2014 Vocabulary: buoyancy, density, graduated cylinder, mass, matter, scale, volume Prior Knowledge Questions (Do these BEFORE using the Gizmo.) Of the objects below, circle the ones you think would float in water. If you cannot circle them on your computer, simply type the names here: Buoyancy Why do some objects float, while others sink? Well to begin with Buoyancy it is common sense that this will have the tendency to float because it has the key words. Gizmo Warm-up The Density Laboratory Gizmo™ allows you to measure a variety of objects, then drop them in water (or other liquid) to see if they sink or float. An object’s mass is the amount of matter it contains. The mass of an object can be measured with a calibrated scale like the one shown in the Gizmo. Drag the first object onto the Scale. (This is object 1.) What is the mass of object 1? 19.5 g An object’s volume is the amount of space it takes up. The volume of an irregular object can be measured by how much water it displaces in a graduated cylinder. Place object 1 into the Graduated Cylinder. What is the volume of object 1? 14.0 mL Note: While milliliters (mL) are used to measure liquid volumes, the equivalent unit cubic centimeters (cm3) are used for solids. Therefore, write the volume of object 1 in cm3. Drag object 1 into the Beaker of Liquid. Does it sink or float? It sinks. Activity A: Float or sink? Get the Gizmo ready: Drag object 1 back to the shelf. Check that Liquid Density is set to 1.0 g/mL. It sinks. Question: How can you predict whether an object will float or sink? Observe: Experiment with the different objects in the Gizmo. Try to determine what the floating objects have in common and what the sinking objects have in common. Form hypothesis: Compare the floating objects, then do the same for the sinking objects. What do the floating objects have in common? The floating objects have in common of weighing more in the graduated cylinder than in the scale. What do the sinking objects have in common? The sinking objects are opposite of the floating objects but the sinking objects have in common of weighing more in the scale than in the graduated cylinder which causes the object to sink. Collect data: Measure the mass and volume of objects 1 through 12, and record whether they float or sink in the table below. Leave the last column blank for now. Object Mass (g) Volume (cm3) Float or sink? Density (g/cm3) 1 2 3 4 5 6 7 8 9 10 11 12 (Activity A continued on next page) ……………………………CONTINUED………………………………………………