Boiling, Freezing, and Melting 5.5B

Boiling—Descriptive When water boils (100ºC), it is changing from a liquid to a gas. Every liquid has its own boiling point. Water boils at the same temperature every time (about 100ºC). When the water boils, small amounts of water evaporate and go into the air. When water evaporates, it changes from a liquid to a gas called water vapor. You can’t see water vapor in the air—it is invisible! The particles in water vapor are very widely spaced out. They mix with other gases in the atmosphere, such as oxygen and nitrogen. Eventually, the water vapor cools and changes back into a liquid. This process is called condensation. Breathe from your mouth onto a mirror and you can see the water vapor in your breath condense to form tiny droplets of liquid water! Prompt: Describe what a pan of boiling water looks like over a 30 minute period. What might you see? What might you feel? What might happen to the water? Use correct science vocabulary.

Boiling—Narrative When water boils (100ºC), it is changing from a liquid to a gas. Every liquid has its own boiling point. Water boils at the same temperature every time (about 100ºC). When the water boils, small amounts of water evaporate and go into the air. When water evaporates, it changes from a liquid to a gas called water vapor. You can’t see water vapor in the air—it is invisible! The particles in water vapor are very widely spaced out. They mix with other gases in the atmosphere, such as oxygen and nitrogen. Eventually, the water vapor cools and changes back into a liquid. This process is called condensation. Breathe from your mouth onto a mirror and you can see the water vapor in your breath condense to form tiny droplets of liquid water! Prompt: Write a story about a water drop that comes out of the faucet and is boiled in a pot. Tell what happens to the water drop and where it goes. Have fun and be creative with this story!

Melting—Persuasive This ice cream is melting and dripping onto the cone and the person’s hand. The air must be above 0 ºC, because we know cold ice cream stays solid below that temperature. Melting happens when a solid is heated and changes to a liquid. Most solids have to be heated to a very high temperature to melt. A few things, like ice cubes or chocolate chips, will melt in your hands. Then they become liquid. When a chocolate chip or an ice cube melts, there is still the same amount of matter—it is just in a different state. A solid has a definite volume and a definite shape, but a liquid takes the shape of its container. If there isn’t a container, the liquid will spread out or drip! Prompt: Do you deserve an ice cream cone today? Write a letter to your parents to tell them why. Use specific reasons to convince them.

Melting—Expository This ice cream is melting and dripping onto the cone and the person’s hand. The air must be above 0 ºC, because we know cold ice cream stays solid below that temperature. Melting happens when a solid is heated and changes to a liquid. Most solids have to be heated to a very high temperature to melt. A few things, like ice cubes or chocolate chips, will melt in your hands. Then they become liquid. When a chocolate chip or an ice cube melts, there is still the same amount of matter—it is just in a different state. A solid has a definite volume and a definite shape, but a liquid takes the shape of its container. If there isn’t a container, the liquid will spread out or drip! Prompt: Explain how to make the best ice cream sundae. Describe each step. What toppings would you add? Would the sundae be a mixture or a solution? Why?