1. Bell Ringer  The mass of a marble is 10 grams. The volume was determined by water displacement to be 3mL. What is the density of the marble?

2. Practice Problem  A graduated cylinder had an original water level of 13mL. A piece of galena, with a mass of 38 grams, was dropped into the graduated cylinder. The water level rose to 18 mL. What is the density of the galena sample?

3.  When the molecules in an object are close together, the material is more dense. 1. Solid – most dense phase

4. 2. Liquid – less dense because molecules are farther apart.

5. 3. Gas – least dense – most space between molecules

6. Density  If an object is more dense than the surrounding liquid it will sink.  If it is less dense it will float.  Which substance is an exception to this rule ? Water Why? Ice (solid) is less dense than water, so it will float

7.  Ex. The diagram below shows a tank filled with water. Wooden blocks of different densities are placed in the tank. Answer the questions that follow. Which block is more dense than water? Why? Which block is less dense than water? Why? Which block could have the same density as water?

8. Most Important!!  The density of a substance under normal conditions doesn’t change even if the size (volume) is different. Ex. Two pieces of clay of different sizes have the same density. Ex. Two cups of water filled to different levels have the same density.