DENSITY  Is the measure of how much mass (matter) is packed into a given space.  Depends on:  Mass  Volume D = m/v (g/cm 3 ) D = m/v (g/cm 3 ) Mass usually expressed in grams Volume usually expressed in cm 3 or liters, etc.

Example  V=57ml  M=373.2 g  What is the Density?

 The proximity of like atoms or molecules  More than just the “heaviness” of a substance, 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

“Compactness”

LIQUIDS  The more dissolved solids in a solution, the more dense (such as ocean water)  Cold water in lakes tend to sink (this creates a constant mixing of water, nutrients, and other substances) Kinetic energy again!! Kinetic energy again!! Denser layers to less dense layers…..

What would happen????  Mercury density = 13600kg/m 3  Lead density = 11340kg/m 3

Lead floats on liquid mercury!

Solids Ice vs. water…..

SOLIDS  Ice is less dense than water (which is why lakes and ponds have a thin layer of ice covering in winter, with water underneath)  Various rocks, woods, metals have a characteristic density specific to that substance Wouldn’t you like to have a bunch of THIS dense material?

Factors affecting Density  Temperature  Pressure

Factors affecting Density  Dissolved solids – in liquids  Concentration and kind of substances

% Error  Density values are found on Table S of your reference table.  The value that you get from taking your measurements is called the “measured value”  The value found in the reference table S, is called the “accepted value”.

% Error= measured value-accepted value x 100 accepted value