Which of the following correctly states the impact of pressure on the behavior of real gases compared to ideal gases?
At low pressure, real gas particles do not exert any force on the container, so they exert less pressure than ideal gases.
At high pressure, real gas particles take up more of the available space, so their volume is greater than ideal gases.
At low pressure, real gas particles expand to fill the container so their volume cannot be measured compared to ideal gases.
At high pressure, real gas particles are squeezed together, so they take up less volume than ideal gases.
The correct answer and explanation is :
The correct statement is:
“At high pressure, real gas particles take up more of the available space, so their volume is greater than ideal gases.”
Explanation:
The behavior of real gases differs from that of ideal gases due to intermolecular forces and the finite volume of gas molecules. The Ideal Gas Law (PV = nRT) assumes that gas particles do not interact with each other and that their volume is negligible compared to the container’s volume. However, real gases deviate from this behavior, especially at high pressures and low temperatures.
- At low pressures, the volume of real gases is close to that of ideal gases because the gas molecules are far apart and intermolecular forces are minimal. Under these conditions, real gases behave similarly to ideal gases, and the volume occupied by the gas particles is negligible compared to the total volume of the container. Hence, the first statement (“real gas particles do not exert any force on the container, so they exert less pressure than ideal gases”) is incorrect. Real gases can still experience attractive and repulsive forces at low pressures, though these effects are minor.
- At high pressures, the gas molecules are forced closer together. Real gas molecules occupy more space because they have a finite volume, which leads to a greater volume than predicted by the Ideal Gas Law. This happens because the attractive forces between molecules become more significant at higher pressures, causing the gas to condense slightly. The gas particles are no longer considered point masses, and their volume must be accounted for. Consequently, the volume of real gas at high pressure will be greater than that of an ideal gas under the same conditions, as real gas molecules cannot be compressed to zero volume.
- The statement “At low pressure, real gas particles expand to fill the container so their volume cannot be measured compared to ideal gases” is also incorrect. Real gases still have a measurable volume at low pressures, though it is nearly the same as the ideal gas volume under these conditions.
Thus, the correct understanding is that at high pressure, the volume of real gases will be larger than that of ideal gases due to the finite size of the molecules and intermolecular forces.