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Density > Determining Density

Density is the ratio of the mass of an object to its volume.

3.4

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Density > Determining Density

Density is an intensive property that depends only on the composition of a substance, not on the size of the sample.

3.4

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Density >

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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Density > 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.

3.4

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SAMPLE PROBLEM

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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

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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 = 2.50 g245 cm3 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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Density > 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.

3.4

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Practice Problems

Problem Solving 3.47 Solve Problem 47 with the help of an interactive guided tutorial.

for Sample Problem 3.10

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SAMPLE PROBLEM

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3.11

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SAMPLE PROBLEM

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3.11

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SAMPLE PROBLEM

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3.11

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SAMPLE PROBLEM

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3.11

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Practice Problems

Problem Solving 3.48 Solve Problem 48 with the help of an interactive guided tutorial.

for Sample Problem 3.11

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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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