Question

You have a shiny metal disc that weighs 1.31 kg that you want to find out what its made of. When you put the disc into a graduated cylinder with 5L in it, you see that the water level rose by about 125 mL. You have a list of densities for various shiny metals: silver= 10.5 g/ mL, nickel= 8.9 g/mL, titanium = 4.5 g/mL, and rhodium = 10.7 g/ mL. What is the disc made of?

Answer 1

The disc is made of silver.

Step-by-step explanation:

To solve this question we need to calculate the metal's density. To do so we need its mass (already given by the problem, 1.31 kg) and its volume.

Following Archimedes' principle, the volume of water displaced by the disk is equal to the disk's volume. This means the metal's volume is 125 mL.

Now we convert 1.31 kg into g, to better compare with the given options:

• 1.31 kg * 1000 = 1310 g

Finally we calculate the metal's density:

• Density = Mass / Volume

• Density = 1310 g / 125 mL = 10.48 g/mL

Looking at the densities given by the problem, the closest one is silver.