Final answer:
To calculate the mass of 17.50 L of propane vapor at STP, we can either use the Ideal Gas Law or the known density at STP. Either method requires finding the number of moles first or directly using the density to find the mass by multiplying the volume by the density.
Step-by-step explanation:
The question asks about the mass of propane vapor at STP. To find the mass of 17.50 L of propane vapor at STP, we need to use the Ideal Gas Law and the known density of propane.
First, we use the Ideal Gas Law which is PV=nRT, where P is the pressure, V is the volume, n is the number of moles, R is the ideal gas constant, and T is the temperature. At STP (Standard Temperature and Pressure), P is 1 atm and T is 273.15 K. The ideal gas constant R in units of L·bar/mol·K is given as 0.08314. However, we need to convert the pressure from atm to bar, because R is given in bar. 1 atm is equivalent to 1.01325 bar. Therefore, we can calculate the number of moles (n) of propane gas using:
n = PV / RT = (1.01325 bar * 17.50 L) / (0.08314 L·bar/mol·K * 273.15 K)
After calculating n, we can find the mass of propane by multiplying the number of moles of propane by its molar mass. The molar mass of propane (C3H8) is 44.09 g/mol.
Mass = n * molar mass of C3H8
The density of propane at STP (1 atm pressure) is also provided as 1.867 g/L. Using density, the calculation can be simplified by multiplying the volume of propane (17.50 L) by its density:
Mass = Volume * Density = 17.50 L * 1.867 g/L