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.