17. Which of the following best explains why the pressure exerted by carbon dioxide on the walls of a sealed container increases when dry ice (solid CO2) sublimates?
Answer: C
Gas CO2 particles occupy more space.
As dry ice sublimates, it transitions from a solid state to a gaseous state, resulting in an increase in the number of gas molecules present in the container. This increase in the number of gas molecules leads to a greater occupation of space and, consequently, an increase in pressure on the container walls.
A) CO2 particles exert less force on the container walls as a gas.
This option is incorrect because gas molecules such as CO2 exert force on the walls of the container based on their velocity and the number of collisions they have with the walls. The force exerted does not decrease when transitioning from solid to gas; rather, it can increase due to the greater number of gas molecules.
B) Gas CO2 molecules move faster when CO2 is a solid.
This statement is inaccurate because solid CO2 molecules do not move in the same way as gas molecules. In a solid state, molecules are tightly packed and vibrate in place. Once sublimated into gas, the CO2 molecules have increased kinetic energy and move much faster, contributing to increased pressure.
C) Gas CO2 particles occupy more space.
This option is correct as it directly addresses the reason for the increase in pressure. When dry ice sublimates, it produces gas that occupies a larger volume compared to its solid form, which leads to a higher density of particles in the container and thus an increase in pressure.
D) CO2 molecules combine to form larger molecules in the gas phase.
This option is incorrect because during the sublimation process, CO2 does not combine to form larger molecules. Instead, the individual CO2 molecules remain as separate entities, and the transition from solid to gas results in more molecules being present, thereby increasing pressure without any molecular combination occurring.
Conclusion
The correct answer is that gas CO2 particles occupy more space, leading to increased pressure as dry ice sublimates. Other options fail to accurately describe the physical changes occurring during sublimation, either misrepresenting the behavior of gas molecules or misunderstanding the fundamental nature of gas pressure dynamics.