Density of Solids

INTRODUCTION

This experiment demonstrates that different solids have different densities. It also illustrates a means of measuring the volume of irregular objects. The identity of unknown metal samples will be determined using density measurement.

MATERIALS

• Metal samples
• Triple beam balances
• Chain necklace or other object of unknown composition
• Graduated cylinders
• Water

WHAT TO DO

1. Measure the weight of each metal cube using a triple beam balance.
2. Discuss possible ways of determining the volume of the cubes. Decide on a method to determine the volume of the cube.
   1. Method 1: Measure the dimension of the cube and calculating the volume.
   2. Method 2: Fill a graduated cylinder half full with water, then gently slide the metal of unknown volume into the graduated cylinder. Then measure the volume increase caused by adding the metal to the graduated cylinder.
3. Using the known densities displayed on the overhead slide, determine the composition of each metal sample. Label each cube with the correct identity.
4. If time permits, take a metal chain and determine if it is really made of gold using the methods you used to study the composition of the metal cubes.

QUESTIONS

1. Is it possible to report the relative densities of the metal cubes with just the weight measurement of each cube? Why or why not?
2. What are the advantages of using the water displacement method?

SOURCE

M. Bailey, OSU Chemistry Dept. Demonstrator.

Metal Density (g/cm³)
Iron 7.87
Lead 11.3
Copper 8.92
Aluminum 2.70
Gold 19.3
Silver 10.5

Density of Other Matter of Interest (g/cm³)
Water 1.00
Air 0.001

© S. Olesik, WOW Project, Ohio State University, 2000.