Freezing, Melting, and Evaporation

SPI 0507.9.2 Describe the differences among freezing, melting, and evaporation.

SPI 0507.9.3 Describe factors that influence the rate at which different types of material freeze, melt, or evaporate.

Part 1 - Definitions Melting Freezing Boiling Evaporating Condensing Sublimating

Melting To melt means to change

a substance from a solid to a liquid state by heating it to the melting point. Different substances melt at different temperatures. Water melts at 0°C or 32°F.

Freezing

To freeze means to change a substance from a liquid to a solid state by cooling it to the freezing point.

Temperatures The freezing and melting temperatures for

most substances are the same. For water this is 0°C or 32°F.

Read Workbook pages 180-181

Boiling Point The boiling point is

the temperature at which a liquid changes to a vapor or gas. Again this is a different temperature for different substances. For water the boiling point is 100°C or 212°F.

Evaporation Evaporation is the change

of a liquid into a vapor at a temperature below the boiling point. This occurs at any temperature between the melting point and the boiling point. However, the warmer the temperature the more quickly the water will evaporate.

Condensation

Condensation is the change of a gas or vapor to a liquid, either by cooling it or by subjecting the substance to an increase in pressure. When water vapor cools in the atmosphere, it condenses into tiny drops of water which form clouds.

Read Workbook page 187

Sublimation

Sublimation is the process of changing from a solid to a gas without passing through a liquid phase.

Read Workbook page 188

Practice – Number your paper from 1 to 10.

Decide the state or phase for each item. Is it . . . Melting Freezing Boiling Evaporating Condensing Sublimating

1. In which state is the snow?

a) Melting

b) Freezing

c) Boiling

d) Evaporating

e) Condensing

f) Sublimating

2. In which state is the puddle? (Choose 2 answers.)

a) Melting

b) Freezing

c) Boiling

d) Evaporating

e) Condensing

f) Sublimating

3. In which state is the fog?

a) Melting

b) Freezing

c) Boiling

d) Evaporating

e) Condensing

f) Sublimating

4. In which state is the moisture on the bottle?

a) Melting

b) Freezing

c) Boiling

d) Evaporating

e) Condensing

f) Sublimating

5. In which state is the puddle on the road?

a) Melting

b) Freezing

c) Boiling

d) Evaporating

e) Condensing

f) Sublimating

6. In which state is the road?

a) Melting

b) Freezing

c) Boiling

d) Evaporating

e) Condensing

f) Sublimating

7. In which state is the moisture on the leaf petals?

a) Melting

b) Freezing

c) Boiling

d) Evaporating

e) Condensing

f) Sublimating

8. In which state is the water in the tea pot?

a) Melting

b) Freezing

c) Boiling

d) Evaporating

e) Condensing

f) Sublimating

9. In which state is the ice next to the mountain?

a) Melting

b) Freezing

c) Boiling

d) Evaporating

e) Condensing

f) Sublimating

10. In which state is the water vapor?

a) Melting

b) Freezing

c) Boiling

d) Evaporating

e) Condensing

f) Sublimating

Answers

1. In which state is the snow?

a) Melting

2. In which state is the puddle?

a) Melting

b) Freezing

3. In which state is the fog?

e) Condensing

4. In which state is the moisture on the bottle?

e) Condensing

5. In which state is the puddle on the road?

d) Evaporating

6. In which state is the road?

b) Freezing

7. In which state is the moisture on the leaf petals?

e) Condensing

8. In which state is the water in the tea pot?

c) Boiling

9. In which state is the ice next to the mountain?

f) Sublimating

10. In which state is the water vapor?

d) Evaporating

Part 2

Factors that influence the rate

of Evaporation

Video

video.flv

video.mp4

Factor 1 - Temperature

The higher the temperature the faster the rate of evaporation.

Which puddle will evaporate faster?

A B

Factor 2 - Wind The more wind or air circulation the faster

the rate of evaporation.

Which puddle will evaporate faster?

A B

Factor 3 – Exposed Surface AreaThe larger the exposed surface area the

faster the evaporation rate.

The water will evaporate more quickly from the beaker on the right with the wider opening.

3 inches1 inch

If each beaker contains 8 ounces of water, which beaker will evaporate the quickest?

Factor 4 - Humidity When humidity (the amount of water vapor

in the air) is high, evaporation is slower.

In which location would laundry hanging on a line dry the quickest?A) Desert

Humidity = 30%

B) Nice Day Humidity =60%

C) Rainy DayHumidity = 100%

D) TropicsHumidity = 90%

Read Workbook page 189

Online Activity

Effect of Humidity & Temperature on Evaporation http://www.fossweb.com/modules3-6/Water/activities/evaporation.dcr

Part 3

Factors that influence the rate of Melting or Freezing

Factor 1 - Temperature

Remember the freezing/melting point of water is 0°C or 32°F.

The higher the temperature the faster water will melt.

The lower the temperature the faster water will freeze.

Factor 2 - Size and Shape

If you have two equal masses of ice – one in a solid block and the other in smaller pieces - the smaller pieces will melt faster.

Factor 2 - Size and Shape (cont.)

Just like with evaporation, the more surface area exposed to heat the faster water will melt. Likewise, the more surface area exposed to cold, the faster water will freeze.

In which cup will the ice melt quicker?

A B

Factor 3 – Conduction Think about this. People control the

temperature of food by placing it into styrofoam containers. Styrofoam is a poor conductor of heat. A styrofoam container will not change temperature quickly. This is why when you buy a cup of hot chocolate, it will probably come in a styrofoam cup. Your hot chocolate will stay warm longer and your hand will not get burned.

Heat Transfer If you place equal amounts of hot water into

two containers - a metal container (a good conductor of heat) and a wooden container (a poor conductor of heat) - the water in the metal container would cool faster.

Cold Transfer

Any time you place equal amounts of water at the same temperature into two containers – one a good conductor of heat and one a poor conductor of heat. The container made from a good conductor of heat will speed up the cooling of the water by conduction.

In which cup could you freeze 6 ounces of water the fastest?

A) plastic B) metal

C) Styrofoam D) wood

Factor 4 – Changing the Composition

During the cold and icy winter, you have probably experienced salt on sidewalks and roads. It is used to melt the ice and snow and keep it from refreezing. The freezing point of water becomes lower as more particles are added until the point where the salt stops dissolving.

By adding salt to icy roads, you change the freezing/melting from 0°C to point to -9°C.

Review – Four Factors that influence the rate of Melting or Freezing

Factor 1 – Temperature (The hotter the air temperature the faster ice melts; the colder the air temperature faster water freezes.)

Factor 2 - Size and Shape (Larger pieces of ice melt more slowly than an equal mass of smaller pieces.)

Factor 3 – Conduction (Water in containers which are good conductors of heat will cool more quickly.)

Factor 4 – Changing the Composition (Mixing water with other compounds such as salt will influence the melting/freezing point.)

Practice – Number your paper from 1 to 12.

Answer the following questions about factors that influence the rate at which different types of material freeze, melt, or evaporate.

1. Falling temperatures can affect the water cycle by ______.

a) creating larger raindrops

b) changing precipitation from rain to snow

c) creating smaller raindrops

d) changing the path of water runoff

2. How does adding salt to water affect the temperature?

a) The melting point increases to a higher temperature.

b) The freezing point increases to a higher temperature.

c) Salt does not affect the temperature of water.

d) The freezing point decreases to a lower temperature.

3. Under which of the following conditions will water evaporate the slowest?

a) Humidity = 95% b) Humidity = 80%

c) Humidity = 30% d) Humidity = 70%

4. You are going camping for three days. You need to buy ice that will keep your ice chest cool for the entire 3 day trip. Which would be the best ice to buy?

a) one large block of ice

b) many small cubes

c) crushed

ice

d) brightly

colored cubes

5. At which of the following ground temperatures will the puddle evaporate the fastest?

a) 50°C b) 15°C

c) 29°C d) 87°C

6. Your little sister forgot to turn off the water in the bathroom sink. The water overflowed and soaked the carpet. You want to dry the carpet out before your mother gets home. At which level should you turn on the fan?

a) low b) high

c) medium d) The carpet would dry out faster without a fan.

7. Students are investigating whether wind affects the rate at which the sponge will dry. Which experiment is best to use in answering their question?

a) b)

c) d)

8. Which cup will keep your coffee hot for the longest amount of time?

a) silver b) copper

c) styrofoam d) steel

9. Each of the following containers hold exactly10 ounces of water. From which container will water evaporate the fastest?

a) b)

c) d)

10. Which letter represents evaporation?

11. At which temperature will the the icicles elt the quickest?

a) 50°C b) 15°C

c) 29°C d) 87°C

12.

Answers

1. Falling temperatures can affect the water cycle by ______.

a) creating larger raindrops

b) changing precipitation from rain to snow

c) creating smaller raindrops

d) changing the path of water runoff

2. How does adding salt to water affect the temperature?

The melting point increases to a higher temperature.

The freezing point increases to a higher temperature.

Salt does not affect the temperature of water.

The freezing point decreases to a lower temperature.

3. Under which of the following conditions will water evaporate the slowest?

a) Humidity = 95% b) Humidity = 80%

c) Humidity = 30% d) Humidity = 70%

4. You are going camping for three days. You need to buy ice that will keep your ice chest cool for the entire 3 day trip. Which would be the best ice to buy?

a) one large block of ice

b) many small cubes

c) crushed

ice

d) brightly

colored cubes

5. At which of the following ground temperatures will the puddle evaporate the fastest?

a) 50°C b) 15°C

c) 29°C d) 87°C

6. Your little sister forgot to turn off the water in the bathroom sink. The water overflowed and soaked the carpet. You want to dry the carpet out before your mother gets home. At which level should you turn on the fan?

a) low b) high

c) medium d) The carpet would dry out faster without a fan.

7. Students are investigating whether wind affects the rate at which the sponge will dry. Which experiment is best to use in answering their question?

a) b)

c) d)

8. Which cup will keep your coffee hot for the longest amount of time?

a) silver b) copper

c) styrofoam d) steel

9. Each of the following containers hold exactly10 ounces of water. From which container will water evaporate the fastest?

a) b)

c) d)

10. Which letter represents evaporation?

11. At which temperature will the icicles melt the quickest?

a) 50°C b) 15°C

c) 29°C d) 87°C

12.