Chemistry - Gases

Ideal Gas

A theoretical gas composed of randomly, noninteracting point particles

Imagine the movement of a single gas molecule inside a container. Explain the particle's motions in terms of kinetic-molecular theory.

Include: --Gas particles act like tiny, solid spheres. --Gas particles are in constant, random motion. --Gas particles obey Newton's laws of motion. --Faster particles collide more often and with more force. --Collisions are elastic, there is no energy lost as the particle hits the sides.

Which observation indicates that the kinetic-molecular theory has limited use for describing a certain gas?

Increasing pressure is causing a smaller change in gas volume.

A substance is made up of slow-moving particles that have very little space between them. Based on this information, what can most likely be concluded about this substance?

It is not a gas because its particles do not have large spaces between them.

Describes gases as a large number of constantly and randomly moving particles (atoms/molecules) that collide with each other and with the walls of the container

Kinetic-molecular theory

Which is an example of the kinetic-molecular theory not holding true for a gas?

The attraction between particles causes a gas to condense at low temperatures.

Effusion

The movement of a gas through a small opening into a larger volume

Diffusion

The spread of particles through random motion from regions of high concentration to regions of low concentration.

Which statement about gases is true? --They are made up of particles that always move very slowly. --They are made up of particles that travel in a curved path when in motion. --They are made up of hard spheres that vibrate quickly in stationary positions. --They are made up of hard spheres that are in random motion.

They are made up of hard spheres that are in random motion.

The closeness of particles of gas and their low speeds allow intermolecular forces to become important at certain pressures and temperatures. Which best describes this statement?

This is a limitation of the kinetic-molecular theory.

Which sequence represents the relationship between temperature and volume as explained by the kinetic-molecular theory?

higher temperature > more kinetic energy > more space between particles > higher volume

According to the kinetic-molecular theory, the collision between two ideal gas particles is a result of

neither attraction nor repulsion.

A chemist is studying the properties of a gas under various conditions. He observes that when the gas is at room temperature and low pressure, it behaves as an ideal gas. When the gas is cooled to 10 kelvin and is placed under high pressure, however, it deviates significantly from an ideal gas. Explain these observations.

Include: --The ideal gas model assumes that gas particles experience no intermolecular attractions. --At low temperature, gas particles move slowly. --At high pressures, gas particles are very close together. --The closeness of the gas particles and their low speed allow intermolecular forces to become important at high pressure and low temperature. --The intermolecular forces cause the gas to deviate from ideal behavior.

Both hydrogen sulfide (H2S) and ammonia (NH3) have strong, unpleasant odors. Which gas has the higher effusion rate? If you opened a container of each gas in a corner of a large room, which odor would you detect first on the other side of the room? Assume the temperature is constant. Explain your answer.

Include: --The molar mass of H2S is greater than the molar mass of NH3, making the velocity and effusion rate of NH3 particles faster. --Effusion rate is inversely proportional to molar mass. --NH3 will have a higher average molecule velocity, so it will diffuse faster and will reach the other side of the room more quickly.

A student checks the air in her bicycle tires early in the morning when it is cool outside. If she measures it again later in the day when it is hotter outside, what will she most likely observe? Explain your answer in terms of kinetic-molecular theory.

Include: --The tire pressure will be higher when the temperature is higher. --Pressure is the result of collisions of gas molecules with the walls of the tire. --Temperature is a measure of the average kinetic energy of the gas molecules. --As temperature increases, gas molecules move more quickly and they collide with the tire walls more frequently and with more force. --Pressure and temperature are directly proportional.

Which statement best describes the compressibility of a gas?

Increasing the pressure on a gas decreases the volume.