H - 2011 Determining if Density is an Extensive or Intensive Property Purpose: Determine if density is an intensive or extensive property. Concepts: Density, uncertain and certain digits, significant digits, percent error, precision and accuracy, and properties of matter including intensive and extensive. (Bibliography: 3 or more sources MLA format) Procedure, Data, and Calculations: Design a lab to determine the density of a substance using the given material. When designing your experiment consider the following: Measure mass with a balance Choose the best method to measure volume: o Ruler: l x w x h o Graduated Cylinder (Water Displacement Method): Vf - Vi Triplicate measurements Record all data with the correct number of significant digits based on the measuring device used. When adding metals to graduated cylinders tip the cylinder to the side and slowly slide the metal into the cylinder. Create a clear data table similar to the one below. Sample Zinc Pellets Zinc Rods Mass 1 Mass 2 Mass 3 Ave Mass Volume 1 Volume 2 Volume 3 Ave Volume Ave Density Zinc Blocks Calculate: Density: D m V Percent Error: %Error measured exp ected 100 exp ected Conclusion Aside from the normal requirements given in your lab report writing standards relate 2 of the major themes of chemistry and real-world applications to the results of your experiment. Discussion Questions for Density Lab 2011 1. What is density and how can you measure it? 2. At the molecular level, how would you describe density? 3. How does a steel ship float when a steel marble sinks? 4. What is the density of (room-temperature fresh) water? Under what circumstances will an object float in water? Under what circumstances will an object sink in water? Support your claims using observational evidence from your own experience. 5. Describe an experiment that would allow you to determine the density of a chair using only the measuring equipment you have at home. Be as specific as you can. In other words, what will you measure? How will you measure it? What calculations will you have to do? 6. What are the two key factors that you could change to increase the density of a substance? Give real-world examples of how you could change both of these characteristics and change an objects’ density, in other words, cause an object to float instead of sink, or to sink instead of float. (Temperature remains constant) 7. How does warming an object affect its size? Support your claim using observation from your own experiences. Does warming an object make its density higher or lower? Why? 8. Which has a higher density, warm water or cold water? Why does one have a higher density than the other? 9. Which has a higher density, fresh water or salt water? Why does one have a higher density than the other?