091 H KMT and States of Matter

Explain why gases are compressible, while liquids are almost completely incompressible.

Gases are compressible because their particles are not as close together as liquids are. Liquids are a condensed state and are far denser than gases.

List several common units of gas pressure.

Millimeter of mercury, torr, pascal, kilopascal, and atmosphere

Which of the following statements is NOT true, according to the kinetic theory? a. There is no attraction between particles of a gas. b. Only particles of matter in the gaseous state are in constant motion. c. The particles of a gas collide with each other and with other objects. d. All of the statements are true.

Only particles of matter in the gaseous state are in constant motion.

What is the difference between boiling point and normal boiling point?

The boiling point is the temperature at which the vapor pressure of a liquid is equal to the external pressure. The normal boiling point of a liquid is the temperature at which the vapor pressure of the liquid is equal to the standard atmospheric pressure of 760 mmHg.

How does the average kinetic energy of an air sample near a campfire compare to air that is far away from it?

The difference in temperatures means there is a difference in how fast the particles are moving.

When a highly volatile (evaporates rapidly) liquid such as acetone is spilled on your skin, it feels cold even if the liquid is originally at room temperature. Explain why this is true.

The evaporating process leaves the remaining perspiration cooler, which, in turn, absorbs more heat from your body.

Explain how the boiling point of a liquid varies with the atmospheric pressure.

The normal boiling point of a liquid is the temperature at which the vapor pressure of the liquid is equal to the standard atmospheric pressure of 760 mmHg. Because atmospheric pressure can change based on location, the boiling point of a liquid changes with the external pressure.

Which of the following statements is part of the kinetic theory? a. The particles of a gas move independently of each other. b. The particles in a gas move rapidly. c. The particles in a gas are relatively far apart. d. all of the above

all of the above

What instrument is normally used to measure atmospheric pressure?

barometer

The average kinetic energy of the particles of a substance ____. a. is not affected by the temperature of the substance b. increases as the temperature of the substance is lowered c. is directly proportional to the temperature of the substance d. is equal to the total energy absorbed by the substance

is directly proportional to the temperature of the substance

What is the SI unit of pressure?

pascal

Particles in a gas are best described as ____.

small, hard spheres with insignificant volumes

What causes gas pressure in a container such as a helium balloon? a. the walls of the container b. the vacuum maintained in the container c. the simultaneous collisions of fast-moving particles in the container d. atmospheric pressure acting on the outside walls of the container

the simultaneous collisions of fast-moving particles in the container

The temperature at which the motion of particles theoretically ceases is ____.

0 K

With which temperature scale is temperature directly proportional to average kinetic energy?

Kelvin

How does the atmospheric pressure at altitudes below sea level compare with atmospheric pressure at sea level? a. The atmospheric pressure below sea level is higher. b. The atmospheric pressure below sea level is lower. c. The pressures are the same. d. Differences in pressures cannot be determined.

The atmospheric pressure below sea level is higher.

What happens to the average kinetic energy of the particles in a sample of matter as the temperature of the sample is decreased?

The average kinetic energy decreases.

How are gases different from liquids and solids in terms of the distance between the particles?

The distance between the particles of a gas is much, much greater than the distances between the particles of a liquid or a solid.

How are the particles arranged in most solids?

They are arranged in an orderly, repeating, three-dimensional pattern.

According to the kinetic theory, collisions between molecules in a gas ____.

are perfectly elastic

A liquid in a closed container has a constant vapor pressure. What can be said about the rate of evaporation of the liquid compared to the rate of condensation of the vapor?

Eventually, the system reaches a point where the rate of evaporation is equal to the rate of condensation.

Explain how a molecule of a liquid evaporates in terms of its kinetic energy. Why does the rate of evaporation increase with temperature?

Molecules of a liquid evaporate even when the temperature of the liquid is below its boiling point. Molecules with high kinetic energies escape the surface of the liquid, leaving the remaining liquid cooler than it was before. Vapor pressure increases as temperature increases due to an increased rate of evaporation.

Which of the following statements is NOT true about the movement of particles in a gas? a. Particles travel in straight-line paths until they collide with other objects. b. Particles usually travel uninterrupted indefinitely. c. Particles fill their containers regardless of the shape or volume of the container. d. The aimless path taken by particles is known as a random walk.

Particles usually travel uninterrupted indefinitely.

What happens to the range of energies of the particles in matter when the temperature is increased? a. The range of energies becomes narrower. b. The range of energies becomes broader. c. The range of energies does not change. d. The range of energies cannot be determined.

The range of energies becomes broader.

Standard conditions when working with gases are defined as ____.

0C and 101.3 kPa

What is one standard atmosphere of pressure in kilopascals?

101.3 kPa

What is an elastic collision?

An elastic collision is one in which there is no overall loss of kinetic energy.

Describe what happens when a solid is heated to its melting point. What phases are in equilibrium at the melting point?

At its melting point, the disruptive vibrations of the particles in the solid overcome the attractive forces operating within the solid. The melting point of a solid is the same as the freezing point of the corresponding liquid. At that temperature, the solid and liquid states of the substance are in equilibrium.