The density of quartz is 165 lb/ft³. A clear crystal with a mass of 26.5 g is found to displace 10.0 cm³ of water. The crystal has a density __________ A) of 2.65 g/cm³ and therefore is most likely quartz. B) of 2.65 g/cm³ and therefore is not quartz. C) of 2.75 g/cm³ and might be quartz. Better measurements are needed for a definitive test. D) of 2.55 g/cm³. Better measurements are needed for a definitive test. E) very different from that of quartz.

Question

Quizplus · Accepted Answer

First, convert the mass of the crystal from grams to pounds:

26.5 g x (1 lb / 453.59 g) = 0.0584 lb

Next, use the displacement of water to find the volume of the crystal:

10.0 cm³ x (1 mL / 1 cm³) x (1 L / 1000 mL) = 0.010 L

The density of the crystal is then:

Density = mass / volume = 0.0584 lb / 0.010 L = 5.84 lb/L

Convert this to lb/ft³:

5.84 lb/L x (1 ft³ / 28.317 L) = 0.206 lb/ft³

This is significantly lower than the density of quartz (165 lb/ft³), so the crystal is not quartz. However, the density of the crystal is 2.65 g/cm³, which indicates that it is likely a different mineral with a similar density to quartz.

The Density of Quartz Is 165 Lb/ft3

The Density of Quartz Is 165 Lb/ft³