Tuesday September 21, 2010

1 / 11

# Tuesday September 21, 2010 - PowerPoint PPT Presentation

Tuesday September 21, 2010. ( Density ). Bell Ringer Tuesday, 9-21-10. A student is working with a material that has its own volume but must take the shape of its container. Which of the following is most likely the identity of the student’s material? a block of marble Coca-Cola

I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.

## PowerPoint Slideshow about 'Tuesday September 21, 2010' - savannah-walker

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.

- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript

Bell RingerTuesday, 9-21-10

A student is working with a material that has its own volume but must take the shape of its container. Which of the following is most likely the identity of the student’s material?

a block of marble

Coca-Cola

nitrogen gas

lightning

Density
• An object made of cork feels lighter than a lead object of the same size.
• What you are actually comparing in such cases is how much mass objects have compared with their size.
• This property is called density - the ratio of mass to volume, or mass divided by volume.
Density

The units for density that we will use most often are:

grams per cubic centimeter (g/cm3) for solids

grams per milliliter (g/mL) for liquids

grams per liter (g/L) for gases

Density
• Density is a physical property of a substance.
• It is an intensive property, in that it does not depend on the size of the sample because as the sample’s mass increases, its volume increases proportionately, and the ratio of mass to volume is constant.
• Density can be used as one property to help identify a substance.
Density

Cork has a density of only 0.24 g/cm3, which is less than the density of liquid water (1.00 g/mL.) Because cork is less dense than water, it floats on water. Lead, on the other hand, has a density of 11.35 g/cm3. The density of lead is greater than that of water, so lead sinks in water.

Density
• Note that Table 2-4 specifies the temperatures at which the densities were measured, because density varies with temperature.
• Most objects expand as temperature increases, thereby increasing in volume.
• Because density is mass divided by volume, density usually decreases with increasing temperature.
Worksheet

Categories, Properties, and Phases of Matter

(Pages 53-54)