Question

2. A 260 em cylinder container was used to collect an undisturbed soil sample. The container and soil weighed 403 g when dried. When empty the container weighed 65 g. What is the bulk density and porosity of the soil? (Hint - The average particle density for mineral soil is usually given as 2.65 g/cm).

Answer 1

Answer:

The Bulk density = 1.3 g/cm³

the porosity of the sample is 132 cm³

Explanation:

Given:

Volume of cylinder = 260 cm³

Mass of container and the soil = 403 g

Mass of the empty container = 65 g

Thus,

The mass of the soil is = 403 - 65 = 338 g  

Now,

The Bulk density = $\frac{\textup{Mass}}{\textup{Volume}}$

or

The Bulk density = $\frac{\textup{338 g}}{\textup{260}}$

or

The Bulk density = 1.3 g/cm³

also,

average particle density for mineral soil is usually given as 2.65 g/cm³

i.e the air present in the given soil sample has reduced its density from 2.65 g/cm³ to 1.3 g/cm³

The mass of the whole sample = Volume × Density

= 260 × 2.65

= 689 gm

but,

The actual mass of the dry sample = 338 g

thus,

Mass of air in the sample = 689 - 338 = 351 g

Therefore,

the volume of 351 g soil = $\frac{\textup{mass defect of soil}}{\textup{density of soil}}$

=  $\frac{\textup{351}}{\textup{2.65}}$

= 132.45 cm³

so the porosity of the sample is 132 cm³