Freezing, Melting, and Evaporation

Freezing, Melting, and Evaporation Agenda: none (make sure you finished your tcap practice questions from Friday—I will take up tomorrow.) Bellwork: What factors do you think will affect the rate at which a material such as water will evaporate, freeze, and melt? Make a list of factors that might affect this. 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.

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 Factors that influence the rate of Evaporation

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?

Factor 3 – Exposed Surface Area The 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. 1 inch 3 inches

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? Read Workbook page 189

Review: What are the factors affecting evaporation?

Part 2 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?

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. Adding salt to water—lowers the freezing point! 

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 ______. • creating larger raindrops • changing precipitation from rain to snow • creating smaller raindrops • 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?

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?

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

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?

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?

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

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

10. Which letter represents evaporation?

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

12.

Answers