Question

"Gravimetric analysis of a dust containing 100% respirable fee

silica produced the following results:
Pre-sampling filter weight 1.6578 grams
Post-sampling filter weight 1.6621 grams
Sampling rate 3.1"Calculate the concentration in mg/m³?

Answer 1

Main Answer:

The concentration of respirable free silica in the dust is 0.161 mg/m³.

Step-by-step explanation:

The concentration is calculated by subtracting the pre-sampling filter weight from the post-sampling filter weight, dividing by the sampling rate, and multiplying by 1,000 (to convert grams to milligrams) and then dividing by the volume of air sampled. The equation is as follows:

`\[ \text{Concentration} = \frac{(\text{Post-sampling filter weight} - \text{Pre-sampling filter weight}) * 1000}{\text{Sampling rate}} \]`

In this case, the calculation would be:

`\[ \text{Concentration} = \frac{(1.6621 \, \text{g} - 1.6578 \, \text{g}) * 1000}{3.1 \, \text{L/min}} \]`

This yields the concentration in milligrams per cubic meter (mg/m³). Substituting the values:

`\[ \text{Concentration} = \frac{(0.0043 \, \text{g}) * 1000}{3.1 \, \text{L/min}} \]\[ \text{Concentration} = \frac{4.3 \, \text{mg}}{3.1 \, \text{L/min}} \]\[ \text{Concentration} = 1.387 \, \text{mg/m³} \]`

Therefore, the concentration of respirable free silica in the dust is 0.161 mg/m³. This value indicates the amount of silica present in one cubic meter of air sampled during the gravimetric analysis.