Cornell Notes 4.1 Density December 21, 2011 Pages 115 and 117

Density Density describes how much mass is in a given volume of a material.

Mass and Volume Remember that mass is defined as how much matter something has. Volume is the amount of space an object takes up. Beach Ball: Small Mass, Big Volume Shotput: Big Mass, Small Volume

What is Density? Dense Not So Dense Density really means how crowded the atoms are in a given substance Dense Not So Dense

Density Solids, liquids and gases are matter, so they all have density.

Density The units used for density depends on whether the substance is solid or liquid. For liquids use units of grams per milliliter (g/mL) For solids use density in units of g/cm3 or kg/m3.

Density of common materials Density is a property of material independent of quantity or shape.

Density of common materials Liquids tend to be less dense than solids of the same material. Water is an exception to this rule. The density of solid water, or ice, is less than the density of liquid water.

Finding Density To find the density of a material, you need to know the mass and volume of a solid sample of the material. Mass is measured with a balance or scale. Use the displacement method or calculate the volume.

Finding Density When calculating volume, all of the units of length involved in the calculation must be the same.

The Formula for Density The formula for density is… Density = Mass ÷ Volume D=m/v

Life and Density Note that if volume is constant, then more mass means more density On the other hand, if mass is constant, then more volume means less density!

Why density varies Density changes for different substances because: Atoms have different masses. Atoms may be “packed” tightly or loosely.