Question

The most common constituent of sand, in inland continental settings and non-tropical coastal settings, is silica (sillicon dioxide or SiO2), usually in the form of quartz. Quartz which has a density of 2.65 g/cm^3 (particle density). The porosity of a material depends upon the grain size and shape. A bucket of sand taken from the dry part of a beach has a mass of 30.0 kg (not including the bucket). When the same bucket is filled with wet sand from just above the water line, the wet sand has a mass of 50.0 kg. This sand is saturated but there in no standing water in the bucket.  

Calculate the porosity of the dry sand.

Answer 1

Porosity = Volume of voids/total volume X 100 %

Volume of sand = mass / density = 30000/2.65

Volume of sand in bucket = 11321 cm³

Mass of wet sand = 50 Kg

Mass of water in the wet sand = 50 - 30 = 20 Kg = 20000

Volume of water in wet sand = mass / density = 20000/1 = 20000 cm³

Total volume of wet sand = volume of sand + volume of water

Total volume of wet sand = 11321 + 20000 = 31321 cm³

Porosity = Volume of voids (water) / total volume of wet sand

porosity = 20000/31321

Porosity = 0.638

Porosity = 63.8 %