The mass of air in the sample is approximately 0.0075 grams, calculated using the product of the negative directional derivative (-0.0362 mL/torr) and the gas constant R (0.0821 L·atm/(mol·K)) at 298 K, divided by the average molecular weight of air (28.8 g/mol).
In this calculation, the negative directional derivative of the V syringe vs. 1/Pair plot serves as a slope that characterizes the relationship between volume and pressure. Given the ideal gas law and the gas constant, the slope is converted into units relevant for gas calculations. Specifically, the product of the negative directional derivative and the gas constant at 298 K is divided by the average molecular weight of air (28.8 g/mol).
The resulting value, approximately 0.0075 grams, represents the mass of air in the sample. The unit consistency throughout the calculation ensures the accuracy of the final mass determination.