Answer:
2.21
Explanation:
At STP, 1 mol of gas has a volume of 22.4 L, so we know we're starting with 1 mol of gas.
Assuming the temperature and volume are held constant, the number of moles needed to reach 325 kPa is found with ideal gas law:
PV = nRT
(325,000 Pa) (0.0224 m³) = n (8.314 Pa m³ / mol / K) (273.15 K)
n = 3.21 mol
Since we started with 1 mol, we need to add 2.21 mol.
