Which of the following gases would be expected to deviate most from ideal behavior under standard conditions?

• A. NH_3
• B. O_2
• C. He
• D. N_2

Answer: (A)

Verified step by step guidance

1. Recall that ideal gas behavior assumes no intermolecular forces and that gas particles occupy no volume. Deviations from ideality occur when these assumptions fail, especially under conditions of high pressure or low temperature.
2. Identify the key factors that cause deviation from ideal gas behavior: strong intermolecular forces (like hydrogen bonding or dipole-dipole interactions) and larger molecular size increase deviation.
3. Examine the molecular properties of each gas: He is a noble gas with very weak London dispersion forces; O_2 and N_2 are nonpolar diatomic molecules with relatively weak intermolecular forces; NH_3 is a polar molecule capable of hydrogen bonding, which is a strong intermolecular force.
4. Since NH_3 has significant hydrogen bonding, it will experience stronger intermolecular attractions compared to the other gases, causing it to deviate more from ideal gas behavior under standard conditions.
5. Therefore, the gas expected to deviate most from ideal behavior is the one with the strongest intermolecular forces, which is NH_3.