1. DENSITY Notebook Page 13

2. Definition Density is the measure of how much mass is contained in a given volume. (Or: how close a substance’s molecules are) The density of a pure substance is always the same, no matter how much of it you have. The density of a substance can change when its temperature changes. Why?

3. International Standards The SI Unit for density is kilograms per cubic meter Most people use grams per cubic centimeter because its better for small sizes. Calculate the volume of “regularly shaped” objects by multiplying length x width x height. If an object is not “regularly shaped”, than it can be placed in water. The amount of water displaced is the volume of the object. Use grams per milliliter.

4. Calculating Density All substances are compared to water The density of pure, fresh water is always 1.0 grams per milliliter. If a substance floats in water, than it is less dense than water. Ex: D = 0.6 g/mL If a substance sinks in water, than it is more dense than water. Ex: D = 2.3 g/mL Density = Mass / Volume or D = M V

5. Why is density important?? Density is one of many physical properties of matter. Density has been used for centuries to identify substances. Yeah! You are done with notes!!! Now, get out another piece of paper.

6. Density Labpg ____ Obj: The student will learn to identify an unknown substance by calculating its density. Materials: Density blocks (or cylinders), metric ruler, graduated cylinder with 50 mL water, digital scale, calculator.

7. Procedure 1. With a partner get a digital scale, a calculator, and either 3 density blocks or 3 density cylinders. 2. Determine if you need a metric ruler or a graduated cylinder with 50mL of water. Get it. 3. Calculate the density of each block or cylinder. 4. Compare it to the list on the board and identify what each block/cylinder is made of.

8. Lab Paper Set-Up Name ___________ 1. My partners were __________________. 2. Hypothesis: If the density of 3 substances are compared, then Block (or Cylinder) _____ will be the most dense and Block (or Cylinder) _____ will be the least dense. 3. Data Table 4. Reflection Questions

9. Data Table - Blocks Block 1Block 2Block 3 Color Texture Length Width Height Volume (cm3) Mass Density Identity of substance

10. Data Table - Cylinders Cylinder 1Cylinder 2Cylinder 3 Color Texture Volume (mL) Mass Density Identity of substance

11. Reflection Questions (you do not need to copy questions) 1. How did you know which volume calculation to use? 2. How many significant figures did you use in each answer and why? 3. Are you confident that you know the identity of each substance? (Yes, No) 4. Why or why not? Explain! 5. Do you think that this skill could be used in the real world? (Yes, No) 6. Why or why not, explain and give example.

12. Possible Substances CylindersDensityBlocksDensity Copper8.9Copper8.9 Brass8.0Brass8.0 Pyrex glass2.23Steel7.6 Rubber1.15Polypropylene0.90 Acrylic1.4Acrylic1.4 Aluminum2.7Aluminum2.7 Nylon1.14Nylon1.14 PVC (polyvinyl chloride)1.50PVC (polyvinyl chloride)1.50 Teflon2.19Wood (pine)0.50 Tecaform1.41Wood (lignum vitae)1.33 Wood (poplar)0.45Wood ( poplar0.45 Wood (Oak)0.75Wood (Oak)0.75