# 2.7: Practice with Density

Exercise $$\PageIndex{1}$$

What is the density of a material if a sample with a mass of 45.82 g takes up a volume of 8.75 mL?

5.24 g/mL

What mass would a sample of 32.6 cm3 of copper be? The density of copper is 8.96 g/cm3.

292 g

What volume of acetone would have a mass of 142.5 g? The density of acetone is 0.784 g/mL.

182 mL

Exercise $$\PageIndex{1}$$

An empty beaker has a mass of 65.873 g. You add 23.8 mL of solution, and the beaker now has a mass of 85.347 g. What is the density of your solution?

0.818 g/mL

You have a rectangular block of metal that measures 4.82 cm long, 3.44 cm wide, and 2.65 cm high. The mass is 197.7 g. What is the density of the metal?

4.50 g/cm3

To a graduated cylinder with 22.5 mL of water you add 38.95 g of metal pieces. The water level rises to 28.0 mL. What is the density of the metal?

7.1 g/mL

Exercise $$\PageIndex{1}$$

You have a copper metal cylinder that is 5.80 cm high. The diameter of the cylinder is 1.44 cm. What would the mass of this cylinder be? The density of copper is 8.96 g/cm3. The formula to calculate the volume of a cylinder is $$V = (\pi)r^2h$$, where $$r$$ is the radius (half the diameter) and $$h$$ is the height. If your calculator doesn't have a button for pi, use the value $$\pi = 3.14159$$.

Hint

The volume of the cylinder is 9.45 cm3. (9.44589... cm3 with 3 significant figures)

84.6 g (If you round the volume to 9.45 cm3, you get 84.7 g. If you keep the digits in your calculator and round at the very end, it is 84.6 g.)

You have a graduated cylinder with the water level at 30.8 mL. You add 72.88 g of copper to the water. The density of copper is 8.96 g/cm3. What is the final water level?

Hint

The volume of copper added is 8.13 cm3, which equals 8.13 mL.

38.9 mL is the water level after the copper is added.

Before you add acetone to a beaker, the mass is 59.43 g. After you add the acetone, the mass is 81.09 g. The density of acetone is 0.784 g/mL. What volume of acetone is in the beaker?

Hint

The mass of acetone added is 21.66 g.