Answer :
The mass of SF6 that can be found in a 15.0-liter tank at STP is 97.7 grams, found by first calculating the number of moles of SF6 and then multiplying by the molar mass of SF6. The correct option is (C) 97.7 g.
The Avogadro's law at STP (standard temperature and pressure), where one mole of any gas occupies 22.4 liters. To determine the amount of SF6 in a 15.0-liter tank at STP, we divide the volume of the tank by the molar volume of a gas at STP:
Number of moles = Volume at STP / Molar volume at STP = 15.0 L / 22.4 L/mol = 0.6696 mol
We then use the molar mass of SF6 (146.06 g/mol) to find the mass:
Mass = Number of moles × Molar mass = 0.6696 mol × 146.06 g/mol = 97.7 g
So, the correct answer is (Option C) 97.7 g.