Question

How many moles of N₂ are in a flask with a volume of 250 mL at a pressure of 300.0 kPa and a temperature of 300.0K?

a) 0.0125 moles
b) 0.025 moles
c) 0.05 moles
d) 0.1 moles

Answer 1

To find the number of moles of N₂ in the flask, the ideal gas law is used with the given conditions and converted to appropriate units, resulting in 0.0125 moles, which corresponds to answer option (a).

Step-by-step explanation:

To determine the number of moles of N₂ in a flask, we can 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. Since we are given that the pressure P is 300.0 kPa which we must convert to atmospheres (1 atm = 101.325 kPa), the volume V is 250 mL, which we must convert to liters (1 L = 1000 mL), and the temperature T is 300.0 K, we can solve for n.

The ideal gas constant R is 0.0821 L.atm.mol⁻¹.K⁻¹, and therefore:

(300.0 kPa / 101.325 kPa/atm) × (250 mL / 1000 mL/L) = n × (0.0821 L.atm.mol⁻¹.K⁻¹) × (300.0 K)

Solving for n we get:

n = (2.9601 atm × 0.250 L) / (0.0821 L.atm.mol⁻¹.K⁻¹ × 300 K)

n = 0.0125 moles

The correct answer to the student's question is option a) 0.0125 moles.