Unit 0 Lesson 5 Check For Understanding
Density Practice Problems
The density of a substance is a measure of how much mass is packed into a certain volume of the substance. Substances with a high density, like steel, have molecules that are packed together tightly. Substances with a low density, like cork, have fewer molecules packed into the same amount of space.
The density of a substance can be found by dividing its mass by its volume. As long as a substance is homogeneous, the size or shape of the sample does not matter. The density will always be the same. This means that a steel paper clip has the same density as a steel girder used to build a bridge.
Density = Mass ÷ Volume D = Mass is in grams, Volume is in mL or cm3
Use the density formula to solve the following problems. Show all work and the answer must have the correct units and significant figures!
- What is the density of CO gas if 0.196 grams occupies a volume of 100.0 mL?
D = m/v
D = 0.196/100
D = .00196
D = .001 g/ml
- A block of wood 3.0 cm on each side has a mass of 27.0 g. What is the density of the block?
Hint: Volume of a cube = L x W x H
3 * 3 * 3 = 27
D = m/v
D = 27/27
D = 1
- An irregularly shaped stone was lowered into a graduated cylinder holding a volume of water equal to 2.0 ml. The height of the water rose to 7.0 ml. If the mass of the stone was 25.0 g, what was its density?
D = m/v
D = 25.0/5.0
D = 5.0
- A 10.0 cm3 sample of copper has a mass of 89.6 g. What is the density of copper?
D = m/v
D = 89.6/10.0
D = 8.96
- 5.0 mL of ethanol has a mass of 3.9 g, and 5.0 mL of benzene has a mass of 44.0 g. Which liquid is denser?
D = m/v
D = 3.9/5.0
D = 0.78
D = m/v
D = 44.0/5.0
D = 8.8
Benzene is denser ( could have seen this obviously just from the numbers )
- A sample of iron has the same dimensions of 2.0 cm x 3.0 cm x 2.0 cm. If the mass of this rectangular-shaped object is 94.0 g, what is the density of iron?
2.0 * 3.0 * 2.0 = 12.0
D = m/v
D = 94.0/12.0
D = 7.83
- What is the mass of ethyl alcohol that fills a 200.0 ml container? The density of ethyl alcohol is 0.789 g/ml.
D = m/v
0.789 = m/200.0
0.789 * 200 = m
m = 157.8
Checking my work:
D = m/v
D = 158.7 / 200.0
D = 0.789
yep im good.
- A flask weighs 345.8 grams and is filled with 225.0 ml of carbon tetrachloride. The mass of the flask and carbon tetrachloride is 703.55 grams. Calculate the density of the carbon tetrachloride.
D = m/v
D = 345.8/703.55
D = 0.4915