Which statement best describes the range where real gases deviate most from ideal behavior?

Which statement best describes the range where real gases deviate most from ideal behavior?

• A. Very high pressures and low temperatures
• B. Very low pressures and high temperatures
• C. All conditions
• D. Ideal gas behavior under all conditions

Answer: (A)

Real gases deviate from ideal behavior because the ideal model treats particles as point particles with no interactions. Two factors matter: the finite size of molecules and the attractions between them. As pressure becomes very high, the space available for each molecule shrinks relative to their actual size, so the volume correction in the ideal gas law breaks down. As temperature drops, intermolecular forces become more significant compared to the molecules’ kinetic energy, so attractions pull molecules together and the pressure for a given volume drops below the ideal prediction. Together, these effects cause the greatest deviation under conditions of very high pressure and low temperature. At very low pressures and high temperatures, particles are far apart and moving quickly, so interactions are minimal and the ideal gas law works well. The idea that deviation occurs under all conditions or that the ideal law holds universally is incorrect.

Real gases deviate from ideal behavior because the ideal model treats particles as point particles with no interactions. Two factors matter: the finite size of molecules and the attractions between them. As pressure becomes very high, the space available for each molecule shrinks relative to their actual size, so the volume correction in the ideal gas law breaks down. As temperature drops, intermolecular forces become more significant compared to the molecules’ kinetic energy, so attractions pull molecules together and the pressure for a given volume drops below the ideal prediction. Together, these effects cause the greatest deviation under conditions of very high pressure and low temperature. At very low pressures and high temperatures, particles are far apart and moving quickly, so interactions are minimal and the ideal gas law works well. The idea that deviation occurs under all conditions or that the ideal law holds universally is incorrect.