Chapter 1 Chemical Foundations 1.8 Density

[Pages:21]Chapter 1 Chemical Foundations 1.8

Density

Copyright ? 2005 by Pearson Education, Inc. Publishing as Benjamin Cummings

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Density

Density

? Compares the mass of an object to its volume. ? Is the mass of a substance divided by its

volume.

Density expression Density = mass = g or g = g/cm3

volume mL cm3 Note: 1 mL = 1 cm3

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Densities of Common Substances

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Learning Check

Osmium is a very dense metal. What is its density in g/cm3 if 50.0 g of osmium has a volume of 2.22 cm3?

1) 2.25 g/cm3 2) 22.5 g/cm3 3) 111 g/cm3

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Solution

Given: mass = 50.0 g volume = 22.2 cm3 Plan: Place the mass and volume of the osmium metal

in the density expression.

D = mass volume

calculator final answer (2)

= 50.0 g 2.22 cm3

= 22.522522 g/cm3 = 22.5 g/cm3

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Volume by Displacement

? A solid completely

submerged in water displaces its own volume of water.

? The volume of the

solid is calculated from the volume difference.

45.0 mL - 35.5 mL

= 9.5 mL = 9.5 cm3

Copyright ? 2005 by Pearson Education, Inc. Publishing as Benjamin Cummings

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Density Using Volume Displacement

The density of the zinc object is then calculated from its mass and volume.

mass = 68.60 g = 7.2 g/cm3 volume 9.5 cm3

Copyright ? 2005 by Pearson Education, Inc. Publishing as Benjamin Cummings

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Learning Check

What is the density (g/cm3) of 48.0 g of a metal if the level of water in a graduated cylinder rises from 25.0 mL to 33.0 mL after the metal is added?

1) 0.17 g/cm3

2) 6.0 g/cm3

3) 380 g/cm3

25.0 mL

33.0 mL object

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