Objective: To calculate density.
- Volume of a cube or block = length x width x height- Volume of irregular shaped object = use water
displacement
Densitydensity = mass/volume OR d = m/v
d =
Example: An object has a mass of 22 g and a volume of 11 cm3. What is the density of this object?
Example #1
1. An object has a mass of 18.9 g and a volume of 7.0 mL. What is the density?
2. What is it? (refer to table of densities on page 17)?
3. Will it float?
Example #1: Answer
1. An object has a mass of 18.9 g and a volume of 7.0 mL. What is the density?
d = m/v = 18.9 g / 7.0 mL = 2.7 g/mL
2. What is it? (refer to table of densities on page 17)?Aluminum
3. Will it float? 2.7 g/mL > density of water (1.0 g/mL) SINK
Example #2
1. A liquid has a mass of 4.743 g and a volume of 6.0 mL. What is the density?
2. What is it (refer to the table of densities on page 17)?
3. Will it float?
Example #2: Answer1. A liquid has a mass of 4.743 g and a volume of 6.0 mL.
What is the density?d = m/v = 4.743 g/6.0 mL = 0.79 g/mL
2. What is it (refer to the table of densities on page 17)?ethanol
3. Will it float?0.79 g/mL < density of water (1.0 g/mL) float
Example #3
What is the density of a cube with a length of 5.0 cm and a mass of 26 g?
Example #3: Answer
What is the density of a cube with a length of 5.0 cm and a mass of 26 g?
Volume = length x width x heightVolume = 5.0 cm x 5.0 cm x 5.0 cm = 125 cm3
Density = m/v = 26 g/125 cm3 = 0.21 g/cm3
Example #4
An irregularly shaped stone was lowered into a graduated cylinder holding a volume equal to 2.0 mL. The height of the water rose to 7.0 mL. If the mass of the stone was 25 g, what was the density?
Example #4: Answer
An irregularly shaped stone was lowered into a graduated cylinder holding a volume equal to 2.0 mL. The height of the water rose to 7.0 mL. If the mass of the stone was 25 g, what was the density?
Volume = 7.0 mL – 2.0 mL = 5.0 mL
Density = m/v = 25 g / 5.0 mL = 5.0 g/mL
Density Equation
• Density = Mass/Volume d = m/v
• Mass = Density x Volume m = d x v
• Volume = Mass/Density v = m/d
Example #5
If the density of an object is 8.7 g/mL and the volume is 15 mL, what is the mass of the object?
Example #5: Answer
If the density of an object is 8.7 g/mL and the volume is 15 mL, what is the mass of the object?
Mass = d x v Mass = 8.7 g/mL x 15 mL Mass = 130.5 g 130 g
Example #6
If the density of an object is 3.6 g/mL and the mass is 60.0 g, what is the volume of the object?
Example #6: Answer
If the density of an object is 3.6 g/mL and the mass is 60.0 g, what is the volume of the object?
Volume = m/d Volume = (60.0 g) / (3.6 g/mL) Volume = 16.67 mL 17 mL
Example #7
If the density of an object is 5.5 g/mL and the mass is 1.2 kg, what is the volume of the object?
Example #7: Answer
If the density of an object is 5.5 g/mL and the mass is 1.2 kg, what is the volume of the object?
Volume = m/d Volume = 1200 g/(5.5 g/mL) Volume = 218 mL 220 mL
Example #8
5.0 mL of the ethanol has a mass of 3.9 g, and 5.0 mL of benzene has a mass of 4.4 g. Which liquid is denser?
Example #8: Answer
5.0 mL of the ethanol has a mass of 3.9 g, and 5.0 mL of benzene has a mass of 4.4 g. Which liquid is denser?
Ethanol BenzeneDensity = Mass/Volume Density = Mass/VolumeDensity = 3.9 g/5.0 mL Density = 4.4 g/5.0 mLDensity = 0.78 g/mL Density = 0.88 g/mL
Benzene is more dense.
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