The ideal gas law best describes the properties of which of the following gases at 0ยฐC and 1 atm?
PH3
HBr
SO2
N2
The Correct Answer and Explanation is :
The ideal gas law is best suited for N₂ (nitrogen) at 0°C and 1 atm among the gases listed (PH₃, HBr, SO₂, and N₂). Here’s why:
Explanation:
The ideal gas law is an approximation that assumes gas particles are point particles (infinitesimally small) that do not interact with each other except through elastic collisions. The equation is:
[
PV = nRT
]
Where:
- ( P ) = Pressure
- ( V ) = Volume
- ( n ) = Moles of gas
- ( R ) = Ideal gas constant
- ( T ) = Temperature in Kelvin
Real gases deviate from ideal behavior due to intermolecular forces (like van der Waals forces) and the actual volume of gas particles. These deviations are more pronounced at high pressures and low temperatures because:
- Intermolecular forces become significant, reducing the effective pressure exerted by the gas molecules.
- Finite molecular size becomes more noticeable when the gas is compressed, reducing the volume available to the gas molecules.
Why N₂ behaves most ideally:
- Small and nonpolar molecules: Nitrogen (N₂) is a small, nonpolar diatomic gas. Nonpolar gases experience very weak intermolecular forces (van der Waals forces), which means N₂ has minimal deviation from ideal behavior.
- At low pressures (like 1 atm): The distance between gas molecules is relatively large, reducing the impact of molecular size and interactions.
- At temperatures near 0°C: Though deviations occur more at lower temperatures, 0°C (273 K) is still sufficiently high for nitrogen to behave almost ideally, especially at 1 atm pressure.
Why the others are less ideal:
- PH₃ (phosphine) and HBr (hydrogen bromide) are polar molecules, meaning they have stronger intermolecular forces, leading to deviations from ideal gas behavior.
- SO₂ (sulfur dioxide) is also a polar molecule and tends to form stronger interactions, further deviating from ideal gas behavior.
Thus, N₂ is the best candidate for ideal gas behavior at 0°C and 1 atm.