The data obtained from an air sample analysis of an old working in a coal mine are given. O2 17.15%, CO2 3.40%, CH4 2.20%, and N2 77.25%. Considering atmospheric air contains O2 20... The data obtained from an air sample analysis of an old working in a coal mine are given. O2 17.15%, CO2 3.40%, CH4 2.20%, and N2 77.25%. Considering atmospheric air contains O2 20.95%, CO2 0.03%, and N2 79.02%, the percentage of blackdamp in the old working is __. (round off up to 2 decimals) Read more

Steps to Solve

1. Understanding Blackdamp Composition

Blackdamp is a mixture of gases that can occur in coal mines, particularly consisting of carbon dioxide (CO2) and nitrogen (N2), with low oxygen (O2) levels. The first step is to calculate the reduction in O2 and the increase in CO2 compared to standard atmospheric air.

2. Calculate the Difference in O2

Subtract the O2 percentage in the mine from the atmospheric O2 percentage: $$ \text{O2 difference} = \text{Atmospheric O2} - \text{Mine O2} $$ $$ \text{O2 difference} = 20.95% - 17.15% = 3.80% $$

3. Calculate the Increase in CO2

Subtract the CO2 percentage of atmospheric air from the mine: $$ \text{CO2 difference} = \text{Mine CO2} - \text{Atmospheric CO2} $$ $$ \text{CO2 difference} = 3.40% - 0.03% = 3.37% $$

4. Calculate Percentage of Blackdamp

Since blackdamp mainly consists of the decrease in O2 and the increase in CO2, we can sum these two differences to find the percentage of blackdamp: $$ \text{Blackdamp} = \text{O2 difference} + \text{CO2 difference} $$ $$ \text{Blackdamp} = 3.80% + 3.37% = 7.17% $$

5. Rounding Off

Round the calculated percentage to two decimal places. Since 7.17% is already at two decimal places, it remains the same.