Assume that you have a sample of gas at 350 K in a sealed container, as represented in (a). Which of the drawings (b)–(d) represents the gas after the temperature is lowered from 350 K to 150 K? The boiling point of the gas is 90 K.

Key Concepts

Kinetic Molecular Theory

The Kinetic Molecular Theory explains the behavior of gases in terms of particles in constant motion. It posits that gas particles are far apart, move freely, and collide elastically. As temperature decreases, the average kinetic energy of the particles also decreases, leading to slower movement and potential phase changes.

Phase Changes

Phase changes refer to the transitions between solid, liquid, and gas states of matter. When a gas is cooled, it may condense into a liquid if the temperature drops below its boiling point. In this scenario, lowering the temperature from 350 K to 150 K, which is above the boiling point of 90 K, suggests that the gas may condense into a liquid state.

Boiling Point

The boiling point is the temperature at which a substance transitions from a liquid to a gas. For the gas in this question, the boiling point is 90 K. Since the initial temperature is 350 K and the final temperature is 150 K, the gas will remain in the gaseous state until it reaches the boiling point, after which it may condense into a liquid.