Final answer:
Using the ideal gas law and converting values to consistent units, the sample of gas at 30.8 liters, 325 K, and 149 kPa contains approximately 1.70 moles.
Step-by-step explanation:
The number of moles of gas present in a 30.8-liter sample at 325 K and 149 kPa can be determined using the ideal gas law, 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.
First, we need to express R in units consistent with the pressure in kPa. The value of R is 8.314 kPa·L/mol·K.
Now, we can use the ideal gas law to solve for n (number of moles):
n = PV / RT
n = (149 kPa × 30.8 L) / (8.314 kPa·L/mol·K × 325 K)
Calculate the value of n:
n = (4588.2 kPa·L) / (2701.61 kPa·L/mol·K)
n ≈ 1.70 moles
The sample contains approximately 1.70 moles of gas.