A piece of metal with a mass of 150. g is placed in a 50 mL graduated cylinder. The water level rises from 20. mL to 42 mL. What is the density of the metal?

Answer 1

The change in volume is 42 - 20 = 22 ml. We will divide this by the mass.

150 grams/ 22 ml = 6.818 gram/mL = 6.8 gram/ml (with correct number of significant figures)

Answer 2

Density is defined as mass divided by volume (in this case, grams divided by milliliters).

You are given the mass of the object as 150. grams

The volume is 42 mL - 20. mL = 22 mL

Divide the mass by the volume to get the density, 150. grams/22 mL = 6.818 grams/mL

Since the smallest number of significant figures you are given is two (from the 20. mL and the 42 mL), you should round the answer off to two significant figures, for a final answer of 6.8 grams/mL.