# Worksheet: Evaporation and Condensation

In this worksheet, we will practice describing the changes that occur when phase changes between liquid and gas occur below boiling temperatures.

Q1:

Fill in the blanks: Condensation is the process in which particles in a combine into liquid droplets suspended in it. If the of the condensed droplets is considerably greater than that of the , the droplets will fall downward.

• Agas, density, gas
• Bgas, speed, gas
• Cliquid, altitude, liquid
• Dgas, temperature, liquid

Q2:

A puddle of water on a road loses one percent of its mass through evaporation. The water temperature remains constant throughout the evaporation.

Does the water heat or cool the air above it during the evaporation?

• ACool
• BHeat

Does the water heat or cool the ground around it during the evaporation?

• ACool
• BHeat

Q3:

Droplets of water condense on a bathroom mirror that is at a lower temperature than the steam in the bathroom. The temperature of the water droplets remains constant throughout the condensation.

Does the condensation of water droplets heat or cool the mirror?

• AIt cools it.
• BIt heats it.

Does the condensation of water droplets heat or cool the air in the bathroom?

• AIt cools it.
• BIt heats it.

Q4:

A hollow solid object is made of particles that are represented by the black dots in the diagram. The solid object contains a liquid made of particles that are represented by the grey dots in the diagram. A small number of particles from the liquid have evaporated and move freely, forming a gas. The liquid is at a constant temperature that is well below its boiling point. Which of the following graphs most correctly shows the distribution of the speeds of the particles in the liquid?

• A
• B
• C
• D

Q5:

A solid surface is made of particles that are represented by the black dots in the diagram. In the space near the surface, there are freely moving gas particles that are represented by the grey dots in the diagram. Some of the gas particles have condensed into liquid droplets. The surface is at a lower temperature than the gas around it.

Fill in the blanks: A typical particle in the gas has a speed than a typical particle in the solid. A typical particle in a liquid droplet has a speed a typical particle in the solid.

• Agreater, greater than
• Bgreater, equal to
• Csmaller, equal to
• Dsmaller, greater than
• Egreater, less than

Fill in the blank: In a collision between a gas particle and the solid, the gas particle’s speed .

• Bincreases
• Cdecreases

Q6:

A hollow, solid object is made of particles that are represented by the black dots in the diagram. The solid object contains a liquid made of particles that are represented by the grey dots in the diagram. The liquid is at a constant temperature that is well below its boiling point. The object also contains a gas made of particles, which are represented by the white dots in the diagram, and some evaporated particles from the liquid.

The top of the object is moved downward. The temperature of the object’s contents remains constant.

Does the lowering of the top of the object increase, decrease, or not change the rate of evaporation of the liquid?

• AThe evaporation rate decreases.
• BThe evaporation rate increases.
• CThe evaporation rate does not change.

Does the lowering of the top of the object increase, decrease, or not change the humidity of the gas?

• AThe humidity increases.
• BThe humidity does not change.
• CThe humidity decreases.

Q7:

A hollow, solid object is made of particles that are represented by the black dots in the diagram. The solid object contains a gas made of particles that are represented by the grey dots in the diagram. The top of the object is lowered until some of the gas particles condense into liquid droplets. The contents of the object remain at a constant temperature throughout the volume change.

Fill in the blanks: When the volume within the object is decreased, the average distance between the particles and the average force exerted on the particles by each other .

• Bdecreases, remains constant
• Cdecreases, decreases

Q8:

The black line in the graph shows the distribution of particle speeds in a gas. After some condensation from the gas occurs, which of the lines I, II, or III most correctly represents the distribution of particle speeds in the gas below the speed at which condensation can occur?

• AIII
• BI
• CII

Q9:

The diagram shows several regions of a graph of temperature versus time for the contents of a container that is heated with constant power. The red line shows the temperature. The container’s contents are initially a solid object that is at its melting point. Throughout the heating process, portions of the object are in different states of matter.

Which regions include the temperature change of the contents of the container due to heating of the gas that is produced by boiling?

• AV and VII
• BV and VI
• CIV, V, VI, and VII
• DII and V
• EVI and VII

Which region includes the temperature change of the contents of the container due to heating of the gas that is produced by evaporation but not by boiling?

• AVI
• BIV
• CII
• DI
• EIII