Day 26 What do liquid water and water vapor have in common? They’re both made up of water particles that move randomly from place to place. How are liquid water and water vapor different? Water vapor particles move faster, bounce harder, and spread out more than liquid water particles. Additional differences students may come up with: You can see liquid water, but water vapor is invisible. Water vapor doesn’t stay in a container like liquid water. Water vapor is compressible, and liquid water isn’t. Daily Warm-Up Exercises Compare Evaporation & Condensation 1

Compare Evaporation and Condensation Contrasting Case Activity 6 Weather & Water, Investigation 6: Water in the Air Compare Evaporation & Condensation

How did Damien get dry without a towel? A Forgotten Towel Damien was swimming on a hot summer day. When he got out of the pool, he saw he had forgotten his towel. Even though it was a hot day, he started to feel cold. He sat in the sun and, a half hour later, he was dry and he felt warm again. How did Damien get dry without a towel? Read the description and the question at the bottom of the slide. Give students a moment to think about it, then tell them they will look at another case before sharing ideas or writing their answers. Compare Evaporation & Condensation

Spilled Water Tameka was carrying a glass of water from the kitchen to her bedroom. As she was walking, she spilled some water on the floor. She forgot about it while she did her homework. When she went back an hour later, the floor was dry. How did the floor get dry? Read the description and the question. Give students a moment to think about it, then distribute the cards (worksheet 21) and have them try to figure out which card best describes what happened in each situation. Encourage them to offer evidence from the cards to support their choices. They should decide that both cases are examples of evaporation. Compare Evaporation & Condensation

Evaporation Water changes from liquid to gas (water vapor) Heat transfers from the environment to water molecules Water molecules gain energy when they evaporate Things “air dry” when liquid water changes to water vapor Introduce evaporation and walk through its characteristics. Compare Evaporation & Condensation

Answer Questions When Damien got out of the pool, he saw he had forgotten his towel. Even though it was a hot day, he started to feel cold. He sat in the sun and, a half hour later, he was dry and he felt warm again. As Tameka was carrying a glass of water to her bedroom, she spilled some on the floor. When she went back an hour later, the floor was dry. Distribute worksheet 22 and have students use the information on the evaporation card to answer the first set of questions. Sample responses: 1. Damien got dry because the water on his skin evaporated. Heat transferred from his skin to the liquid water molecules, and that's what made him feel cold. When the liquid molecules gained energy, they changed to water vapor and joined the surrounding air. 2. The floor got dry because the water on the floor evaporated. Heat transferred from the floor and surrounding air to the liquid water molecules. When the liquid molecules gained energy, they changed to water vapor and joined the surrounding air. 3. Both situations are examples of evaporation. Both involve liquid water molecules gaining energy from the environment and changing to water vapor. Compare Evaporation & Condensation

Question 1 How did Damien get dry? The water on his skin evaporated. He felt cold because heat transferred from his skin to the liquid water molecules. When the liquid molecules gained energy, they changed to water vapor and joined the surrounding air. Compare Radiation & Conduction Compare Evaporation & Condensation 7

Question 2 How did the floor get dry? The water on the floor evaporated. Heat transferred from the floor and surrounding air to the liquid water molecules. For question 3, students should say that both are examples of evaporation. Both involve liquid water molecules gaining energy from the environment and changing to water vapor. When the liquid molecules gained energy, they changed to water vapor and joined the surrounding air. Compare Radiation & Conduction Compare Evaporation & Condensation 8

The Water Stain Raymond’s grandmother always scolded him for not using coasters to protect the table from water stains. One humid day, he poured a cold glass of soda and wiped the glass with a towel. The glass was dry when he set it down. Ten minutes later, the glass was wet and there was a water stain on the table. How did the table get wet? Read the description and the question. Give students a moment to think about it, then go on to the next case. Compare Evaporation & Condensation

Jasmine Sees her Breath Jasmine stepped outside one cold winter morning. As she walked, she noticed little clouds forming when she breathed. She wondered why she could only see her breath on cold mornings and not in summer, when the air is warm. Why did Jasmine see her breath? Read the description and the question. Give students a moment to think about it, then go to the next slide. Compare Evaporation & Condensation

Condensation Water vapor in the air changes from gas to liquid Heat transfers from water molecules to the environment Water molecules lose energy when they condense Glasses "sweat" when water vapor changes to liquid water moist air Introduce condensation and review its characteristics. Compare Evaporation & Condensation

Answer Questions Raymond poured himself a cold glass of soda. The glass was dry when he set it down. Ten minutes later, the glass was wet and there was a water stain on the table. One cold winter morning, Jasmine noticed little clouds forming when she breathed. She wondered why she could only see her breath on cold mornings and not when the air is warm. Have students answer the second set of questions. Sample responses: 1. The table got wet because water vapor in the surrounding air condensed. Heat transferred from the water vapor molecules to the cold glass. When the vapor molecules lost energy, they changed to liquid water that collected on the outside of the glass and dripped down on the table. 2. Jasmine saw her breath because of the condensation of water vapor in the air she was exhaling. Heat transferred from the water vapor to the cold air around her. When the vapor molecules lost energy, they changed to droplets of liquid water that formed a visible cloud. 3. Both situations are examples of condensation. Both involve water vapor molecules losing energy to the environment and changing to liquid water. Compare Evaporation & Condensation

Question 4 How did the table get wet? Water vapor in the surrounding air condensed. Heat transferred from the water vapor molecules to the cold glass. When the water vapor molecules lost energy, they changed to liquid water molecules that collected on the glass and dripped down onto the table. Compare Radiation & Conduction Compare Evaporation & Condensation 13

Question 5 Why did Jasmine see her breath? As she exhaled, water vapor in the air from her lungs condensed. Heat transferred from the water vapor molecules to the cold air around her. For question 6, students should say that both are examples of condensation. Both involve water vapor molecules losing energy to the environment and changing to liquid water. When the water vapor molecules lost energy, they changed to liquid water molecules that collected in droplets to form a visible cloud. Compare Radiation & Conduction Compare Evaporation & Condensation 14

Evaporation vs. Condensation Use your Evaporation and Condensation cards to compare and contrast the two processes. Warm air Distribute worksheet 23 and have students use the cards to complete the Venn diagram. Compare Evaporation & Condensation

Evaporation vs. Condensation Both Water changes from liquid to gas (water vapor) Water changes state Water vapor in the air changes from gas to liquid Heat transfers Heat transfers from the environment to water molecules Heat transfers from water molecules to the environment Water molecules gain or lose energy Water molecules gain energy Sample answers will appear on keypress. The environment gains or loses energy Water molecules lose energy Things "air dry" Glasses "sweat" Compare Evaporation & Condensation