The Foundations of Chemistry

EXAMPLE 1-12 Density, Mass, Volume

If 116 g of ethanol is needed for a chemical reaction, what volume of liquid would you use?

Plan

We determined the density of ethanol in Example 1-11. Here we are given the mass, m, of a

sample of ethanol. So we know values for Dand min the relationship

D

We rearrange this relationship to solve for V, put in the known values, and carry out the

calculation. Alternatively, we can use the unit factor method to solve the problem.

Solution

The density of ethanol is 0.789 g/mL (Table 1-8).

D
 ,soV


147 mL

Alternatively,

__?mL
116 g
147 mL

You should now work Exercise 39.

EXAMPLE 1-13 Unit Conversion

Express the density of mercury in lb/ft^3.

Plan

The density of mercury is 13.59 g/cm^3 (see Table 1-8). To convert this value to the desired

units, we can use unit factors constructed from the conversion factors in Table 1-7.

1 mL



0.789 g

116 g



0.789 g/mL

m



D

m



V

m



V

These densities are given at room
temperature and one atmosphere
pressure, the average atmospheric
pressure at sea level. Densities of solids
and liquids change only slightly, but
densities of gases change great]y, with
changes in temperature and pressure.

32 CHAPTER 1: The Foundations of Chemistry

Observe that density gives two unit

factors. In this case, they are 

0

1

.7

m

89

L

g



and 
0

1

.7

m

89

L

g



TABLE 1-8 Densities of Common Substances*

Substance Density (g/cm^3 ) Substance Density (g/cm^3 )

hydrogen (gas) 0.000089 sand* 2.32

carbon dioxide (gas) 0.0019 aluminum 2.70

cork* 0.21 iron 7.86

oak wood* 0.71 copper 8.92

ethyl alcohol 0.789 silver 10.50

water 1.00 lead 11.34

magnesium 1.74 mercury 13.59

table salt 2.16 gold 19.30

*Cork, oak wood, and sand are common materials that have been included to provide familiar reference points. They

are notpure elements or compounds as are the other substances listed.