1 2.8 Density Density Calculations Copyright © 2005 by Pearson Education, Inc. Publishing as...
-
Upload
elinor-russell -
Category
Documents
-
view
230 -
download
3
Transcript of 1 2.8 Density Density Calculations Copyright © 2005 by Pearson Education, Inc. Publishing as...
1
2.8
Density
Density Calculations
Copyright © 2005 by Pearson Education, Inc.Publishing as Benjamin Cummings
2
Density
• Compares the mass of an object to its volume
• Is the mass of a substance divided by its volume
Density expressionD liquids = mass = g or g = g/cm3
volume mL cm3
D solids = kg or kg = kg/L L m3
Note: 1 mL = 1 cm3
Density
Review the steps for problems:
1.Circle information
2. DMV it
3. Put in triangle
4. Solve
5. Add units
5
Osmium is a very dense metal. What is its density in g/cm3 if 50.0 g of osmium has a volume of 2 cm3?
1) 2.5 g/cm3
2) 25 g/cm3
3) 100 g/cm3
Learning Check
6
Given: mass = 50.0 g volume = 2 cm3
Plan: Place the mass and volume of the osmium metalin the density expression.
D = mass = 50.0 g volume 2 cm3
Calculator = 25 Final answer (2) = 25 g/cm3
Solution
7
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
8
Density Using Volume Displacement
The density of the zinc object isthen calculated from its massand volume.
mass = 68.60 g = 7.2 g/cm3 volume 9.5 cm3
Copyright © 2005 by Pearson Education, Inc.Publishing as Benjamin Cummings
9
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
Learning Check
10
Given: 48.0 g Volume of water = 25.0 mL Volume of water + metal = 33.0
mLNeed: Density (g/mL)
Plan: Calculate the volume difference. Change to cm3,
and place in density expression.
33.0 mL - 25.0 mL = 8.0 mL
8.0 mL x 1 cm3 = 8.0 cm3
1 mLSet Up Problem:
Density = 48.0 g = 6.0 g = 8.0 cm3 1 cm3
Solution
6.0 g/cm3
11
If olive oil has a density of 0.5 g/mL, how many milliliters of olive oil are in 18 g of olive oil?
1) 3.6 mL
2) 36 mL
3) 9 mL
Learning Check
12
Given: D = 0.5 g/mL mass = 18 g
Need: volume in liters
Plan: Volume is mass divided by density
Set Up Problem:
18 g x 1 mL = 0.5 g density
factor
Solution
36 mL
13
Which of the following samples of metals will displace the greatest volume of water?
1 2 3
25 g of aluminum2.70 g/mL
45 g of gold19.3 g/mL
75 g of lead11.3 g/mL
Learning Check
14
1Plan: Calculate the volume for each metal and select the metal sample with the greatest volume.
1) 25g x 1 mL = 9.3 mL aluminum2.70 g
2) 45 g x 1 mL = 2.3 mL gold19.3 g
3) 75 g x 1 mL = 6.6 mL lead11.3 g
Solution
25 g of aluminum2.70 g/mL
Problem 1
What is the density of an object with a mass of 60 g and a volume of 2 cm3?
Density= mass = 60g =
volume 2 cm3
30 g/cm3
Problem 2
If you have a rectangular gold brick that is 2 cm by 3 cm by 4 cm and has a mass of 48 g, what is its density?
Problem 2
If you have a rectangular gold brick that is 2 cm by 3 cm by 4 cm and has a mass of 48 g, what is its density?
Volume= length x width x height
2 cm x 3 cm x 4 cm =
Density= mass = 48 g =
volume 24 cm3
24 cm3
2 g/cm3