Chem-To-Go Lesson 3Unit 1DENSITY

DENSITY IS A PHYSICAL PROPERTY.

AluminumDensity = 2.8

g/cm3

SilverDensity = 10.49

g/cm3

ZincDensity = 5.61

g/cm3

Notice: The 3 substances look alike. Physical property doesn’t just refer to appearance.

Density is a simple physical property that has nothing to do with appearance. Instead, density is

a ratio of mass over volume. It can be used to identify substances.

Three Simple Steps:1) Measure mass.2) Measure volume.3) Divide mass by volume.

FINDING DENSITY

D = M V

On October Break, a student goes mining for gold in the North Georgia mountains. He sifts the silt and water in a creek bed and finds a shiny, golden metal. Did he strike it rich?

Mass of his fi nding: 103,255 mgVolume of his fi nding: 5.35 mLDensity of gold: 19.30 g/mL

EASY DENSITY EXAMPLE

Calculate the density of his finding. Is it gold?

TIP: Since we’re going to compare to a given density, we need to make sure that our units match.

What is the mass of a block whose density is 0.78 g/cm3 and volume is 324 mm3?

MORE ADVANCED DENSITY EXAMPLE

Given Information:

Density of block = 0.78 g/cm3

Volume of block = 324 mm3ALWAYS CHECK THE

DENSITY UNITS IF GIVEN.

DO THE UNITS MATCH?

SOLUTION:1. MAKE ALL UNITS MATCH THE

DENSITY UNITS.2. PLUG INTO THE EQUATION.3. SOLVE THE PROBLEM USING

BASIC ALGEBRA.