Activity 6

WHAT IS DENSITY?

Purpose

The purpose of this activity is to understand the definition of density, to calculate the density of a substance, and to understand the difference between extensive and intensive properties.

Introduction

Density is defined as the mass of a substance divided by its volume. Any pure substance will have a characteristic density whether the substance is a solid, liquid, or gas. Density is a function of temperature, but the dependence is much greater for a liquid than a solid and for a gas than a liquid. For a gas, density is also noticeably dependent on atmospheric pressure.

Instructions

You will be given a lump of clay. Shape the clay into a three dimensional block and measure its length, width and height. Record these numbers on the report sheet, then calculate the volume of the block. Measure the mass of the block on a balance and calculate the density of the block. Show all calculations clearly and neatly on the report sheet.

Cut off a section of the block. Measure the new length, width, height, and mass. Re-calculate the volume and density of the block.

Repeat this action two more times.

Report Sheet

WHAT IS DENSITY?

Trial	Length (cm)	Width (cm)	Height (cm)	Volume (cm^3)	Mass (g)	Density (g/cm^3)
1
2
3
4
5

Sample Calculations

Questions

1) Sketch a graph of volume on the X axis versus mass on the Y axis in the space below.

2) How can the density of the clay represented on the graph?

3) Density is an intensive property. Based on the data recorded, what do you think that means?

4) Mass is an extensive property. What do you think that means, and why is mass extensive?

5) Why is it important to know if a property is extensive or intensive?