How many moles are contained in 3.25 L sample of an ideal gas at 25oC and 204 kPa?
PV = nRT
If you use kPa for P, use 8.314 for R. Remember T must be in kelvin.
To determine the number of moles in a sample of an ideal gas, we can use the Ideal Gas Law equation:
PV = nRT
Where:
P = pressure (in atmospheres, but can be converted)
V = volume (in liters)
n = number of moles
R = ideal gas constant (0.0821 L.atm/(mol.K) at normal conditions)
T = temperature (in Kelvin)
First, we need to convert the given temperature from Celsius to Kelvin:
T(K) = T(°C) + 273.15
T = 25°C + 273.15
T = 298.15 K
Next, we need to convert the given pressure from kilopascals (kPa) to atmospheres (atm):
1 atm = 101.325 kPa
P(atm) = P(kPa) / 101.325
P(atm) = 204 kPa / 101.325
P(atm) ≈ 2.01 atm
Now we have all the values we need to solve for n (number of moles):
PV = nRT
n = PV / RT
n = (2.01 atm)(3.25 L) / (0.0821 L.atm/(mol.K))(298.15 K)
n ≈ 0.271 moles
Therefore, there are approximately 0.271 moles of gas in the 3.25 L sample at 25°C and 204 kPa.