Question

John uses a balance to determine the mass of a rock is 6.5 grams. A graduated bottle contains 10.0 milliliters of water. When the rock is carefully lowered into the graduated bottle and is completely covered with water the volume of the water containing the marble has increased to 12.2 milliliters. Find the density of the rock. (round to the nearest tenth if necessary).

A. 2.95 g/mL
B. 295.4 g/L
C. 29545 g/L
D. 2954.5 g/L

Answer 1

The density of the rock is found by dividing its mass (6.5 grams) by the volume it displaces (2.2 mL), resulting in a density of 3.0 g/mL after rounding to the nearest tenth.

Step-by-step explanation:

To find the density of the rock, you need to calculate the mass divided by the volume it displaces. The mass of John's rock is 6.5 grams, and the volume displacement after submersion in water is 12.2 mL - 10.0 mL, which is 2.2 mL (because 1 mL of water is equivalent to 1 cm³). Therefore, the density ρ is calculated as follows: ρ = mass / volume = 6.5 g / 2.2 mL = 2.9545 g/mL. When rounded to the nearest tenth, the density is 3.0 g/mL. For comparison, the density of a 240-g rock that displaces 89.0 cm³ of water would be 240 g / 89.0 cm³ = 2.70 g/cm³, showing a similar process to find density.