1. + Density Austin High School Chemistry Ms. Gutierrez 2015-2016

2. + Density One of the most important physical properties of matter is density.  Density is the measurement of how tightly packed matter is (how much weight is in a specific volume).  Density is the ratio of mass to volume  If the volume stays the same and the mass increases... the density will increase  If the mass stays the same and the volume increases... The density will decrease

3. + DENSITY EQUATION D = m/v Density = mass/ Volume Mass is measured in grams (g). Volume is measured in units of length cubed (cm 3 ) or units of volume (L or mL). Units for density are typically either g/cm 3, g/L, or g/mL. Since the amount of matter is mass and the space it occupies is volume we can calculate the density of matter using the following equation:

4. How close the atoms or molecules are to each other More than “heaviness” - density includes how much space an object takes up!! All substances have density including liquids, solids, and gases Density is the measure of the “compactness” of a material

5. + Mass Mass: Amount of matter in a substance. Mass is measured using a balance (triple-beam or electrical) The metric base unit for mass is grams (g).

6. + Volume The amount of space that a substance or object takes up. Volume can be calculated (L x W x H) or measured using water displacement. Metric base unit for volume is the liter (L).

7. + The “DMV” Triangle for Volume, Mass, and Density M ÷ ÷ D X V Density = MVMV Volume = MDMD Mass = D x VD x V

8. + Density Example Problem #1 You have 15 grams of an elemental metal. The metal has a volume of 2.5 mL. What is the density of your metal?

9. + Density Example #2 Poplar wood has a density of 0.45 g/mL. What would be the volume of a piece of poplar wood that has a mass of 200 grams (g).

10. + Density Example #3 A sample of aluminum has a density of 2.7 g/cm 3. What is the mass of this sample if its volume is 5.5 cm 3.

11. + Buoyancy buoyancy is the ability of a solid object to float. Therefore, it is closely related to density. For liquids and gases, density is the only consideration for one material to “float” on another. Liquid/gases that are less dense will float to the top and liquid/gases that are more dense (have higher density) will sink. The density of water is roughly 1 g/mL. Copper has a density of 8.9 g/mL. Since copper is more dense it will sink in water. Pine wood however has a density of 0.35 g/mL, so it will float in water.