The Foundations of Chemistry

Solution

__?
13.59 

3



3


 848.4 lb/ft^3

It would take a very strong person to lift a cubic foot of mercury!

The specific gravity(Sp. Gr.) of a substance is the ratio of its density to the density
of water, both at the same temperature.

Sp. Gr.

The density of water is 1.000 g/mL at 3.98°C, the temperature at which the density of
water is greatest. Variations in the density of water with changes in temperature, however,
are small enough that we can use 1.00 g/mL up to 25°C without introducing significant
errors into our calculations.

EXAMPLE 1-14 Density, Specific Gravity

The density of table salt is 2.16 g/mL at 20°C. What is its specific gravity?

Plan

We use the preceding definition of specific gravity. The numerator and denominator have the
same units, so the result is dimensionless.

Solution

Sp. Gr.


2.16

2.16 g/mL



1.00 g/mL

Dsalt



Dwater

Dsubstance



Dwater

12 in.



1 ft

2.54 cm



1 in.

1 lb



453.6 g

g



cm^3

lb



ft^3

Density and specific gravity are both

intensive properties; that is, they do

not depend on the size of the sample.

Specific gravities are dimensionless

numbers.

1-11 Density and Specific Gravity 33

Ice is slightly less dense than liquid
water, so ice floats in water.

Solid ethyl alcohol is more

dense than liquid ethyl alco-

hol. This is true of nearly

every known substance.