There is a problem: given the saturated vapor pressure at a certain temperature, and knowing that it is carried away by purging with dry air at atmospheric pressure, how can its concentration be determined?

Since the saturated vapor pressure is known, we can calculate the vapor pressure of toluene at that temperature using its formula. Then, using the ideal gas law PV=nRT and the fact that the mole fractions of nitrogen and oxygen in dry air are 79% and 21%, it is possible to calculate the number of moles of toluene molecules in a given volume of dry air. Thereby, the concentration of toluene in dry air is obtained. The specific calculation method is as follows: 1. To calculate the vapor pressure P of toluene (in mmHg), use the formula P=10^(A-B/(C+t)), where A=6.95464, B=1344.800, C=219.483, and t is the given temperature (°C). 2. Using the ideal gas law PV=nRT, calculate the amount of moles n (in units of mol) of toluene in a given volume. Assuming the volume of air is V and the molar fraction of toluene is x, then: P_toluene = x·P_total_pressure = xnRT/V. Here, P_total_pressure is the atmospheric pressure at standard conditions, which can be taken as 760 mmHg ； R is the gas constant, taken as 0.0821 L·atm/mol·K. Solving the above equation yields the molar amount n of toluene in a certain volume of dry air. 3. Calculate the concentration c of toluene (in units of mol/L). The concentration of toluene in dry air can be obtained by dividing the molar amount n of toluene by the volume V of air. c = n/V. Note that the unit here is mol/L; therefore, the volume of air V needs to be converted into liters (L). In summary, we can calculate the concentration of toluene in dry air using the known vapor pressure of toluene, the ideal gas law, and data on the composition of air. .