3.4
Density
>
Determining Density
Density is the ratio of the mass of an object to
its volume.
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3.4
Density
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Determining Density
Density is an intensive property that
depends only on the composition of a
substance, not on the size of the
sample.
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Density
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So, the density for a given substance
defines the relationship between mass
and volume
Like any relationship, it gives you 2
conversion factors
For gold,
19.3 g/cm3 and 1 cm3/19.3 g
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3.4
Density
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Determining Density
The density of corn oil is
less than the density of
corn syrup. For that
reason, the oil floats on
top of the syrup.
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SAMPLE PROBLEM 46
A student finds a shiny piece of metal that she thinks
is aluminum. In the lab, she determines the metal
has a volume of 245 cm3 and a mass of 612 g. Is
this metal aluminum?
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SAMPLE PROBLEM
Well, we can find the density of the material and
compare it to the density in the table for aluminum
and see if they match.
612 g
245 cm3
=
2.50 g
cm3
From the table, the density of aluminum is 2.70
g/cm3, so no the metal is not pure aluminum
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3.4
Density
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Density and Temperature
Experiments show that the volume of most
substances increases as the temperature
increases. Meanwhile, the mass remains
the same. Thus, the density must change.
The density of a substance generally
decreases as its temperature
increases.
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Practice Problems for Sample Problem 3.10
Problem Solving 3.47 Solve
Problem 47 with the help of an
interactive guided tutorial.
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SAMPLE PROBLEM 3.11
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SAMPLE PROBLEM 3.11
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SAMPLE PROBLEM 3.11
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SAMPLE PROBLEM 3.11
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Practice Problems for Sample Problem 3.11
Problem Solving 3.48 Solve
Problem 48 with the help of an
interactive guided tutorial.
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3.4 Section Quiz
1. If 50.0 mL of corn syrup have a mass of 68.7
g, the density of the corn syrup is
a. 0.737 g/mL.
b. 0.727 g/mL.
c. 1.36 g/mL.
d. 1.37 g/mL.
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3.4 Section Quiz
2. What is the volume of a pure gold coin that
has a mass of 38.6 g? The density of gold is
19.3 g/cm3.
a. 0.500 cm3
b. 2.00 cm3
c. 38.6 cm3
d. 745 cm3
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3.4 Section Quiz
3. As the temperature increases, the density of
most substances
a. increases.
b. decreases.
c. remains the same.
d. increases at first and then decreases.
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