Lesson Overviewfor Teachers

View the video clip below to see what you and your students will do in this lesson.

You are watching: Is water heated up a chemical change


Downloadables:Lesson arrangement (PDF) |Student activity Sheet (PDF) |Teacher background (PDF) |Connections come NGSS(PDF)


Objective

Students will be able to explain the cooling water can change it to ice and also that heating ice cream can adjust it ago to liquid water. Students will be able to explain the this process can additionally happen to various other substances. Students will likewise be may be to explain that heater a substance provides its molecules move faster and also cooling a substance renders its molecules move slower. The great can likewise be offered to lay a foundation for learning around changes in state and also chemical changes which can be further emerged in later on grades.

Key Concepts

If water is cooled enough it can readjust to ice.If ice is warmed enough, the can readjust to fluid water.Heating a substance renders the molecules relocate faster.Cooling a substance renders the molecules move slower.

NGSS Alignment

NGSS 2-PS1-4:Construct an dispute with evidence that some transforms caused by heating and also cooling have the right to be reversed and some cannot.

Summary

Students check out a video clip of water freezing and then melting.Students warmth butter till it melts and then cool it till it turns hard again.Students watch an animation showing that heat reasons the molecules in butter to relocate faster and separate from every other. They likewise see that cooling butter makes the molecule move much more slowly and come back together.Students take part in a class discussion around how heating and cooling can reason changes in matter.

Evaluation

Download the Student activity Sheet (PDF) and distribute one per student as soon as specified in the activity. The activity sheet will certainly serve together the evaluate component that the 5-E class plan.

Safety

Be certain students wear correctly fitting goggles.

Materials because that each group

Small plastic cup v ¼ tespoon of butter in it2 Popsicle sticksCup for warm waterCup for ice water

ENGAGE

1. Show a time lapse video of water freezing and ice melt to introduce the idea that cooling and also heating can reason a change in a substance.

Ask students:What can happen to water if you do it yes, really cold?The water have the right to turn into ice.

Explain to students that as soon as water freezes, it alters from a liquid to a solid.


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Show the moment lapse video Water Freezing. 

Note: Tell students that this is a special type of video in which something that takes a long time can be shown in a much much shorter time. The freezing of the water in the glass more than likely took at least six hours. The video was taken for the entirety six hours however is displayed speeded increase so the the freezing procedure can be presented in about 1 minute. Phone call students the this form of video is called “time lapse”.


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Show the time lapse video Ice Melting.

Explain the warming ice renders it change from solid ice to fluid water.

Note: Students may not realize that the ice is being warmed just by being at room temperature. They may expect to view the ice put on the stove or held over a candle flame. Define to students that the ice cream is being warmed because it is at regular room temperature and that room temperature is warmer than the temperature the the ice. Typically ice demands to it is in in a freezer in ~ a short temperature or outside in cold weather (32 °F or 0°C or lower) to continue to be frozen as ice. If it is placed on a surface in a room at regular temperature, it is actually being warmed.

Explain to students that water deserve to be cooled to make ice and then the ice have the right to be warmed to make liquid water again. Cooling and also heating water in this way can do the transforms go ago and forth.


Give each college student anActivity sheet (PDF).Students will record their observations and answer questions around the activity on the task sheet.


EXPLORE

2. Have students inspection what happens when butter is heated.

Question to Investigate: How does butter readjust when you warm and cool it?

Materials because that each groupSmall plastic cup v ¼ teaspoon of butter in it2 Popsicle sticksCup for hot waterCup for ice cream water

Have students pertained to the front of the class. Present students a rod of butter at room temperature. Usage a popsicle stick to display that the is soft and can be reduced easily.

Ask studentsHow execute you think the butter will readjust if you warm it?If it is heated enough it will melt and also become a liquid.

Explain come students that once scientists have actually a inquiry they carry out an investigation to try to discover the answer. Phone call students the they deserve to be the scientists and also do an investigation to discover the answer come the question.


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Procedure
Carefully press your plastic cup with the butter a little method into the warm water cup.Use the popsicle pole to move the butter around in the bottom of the cup. If the butter gets stuck ~ above the popsicle stick, use the other popsicle rod to press the butter earlier down right into the cup.Keep the cup in the warm water and also keep stirring till you check out a readjust in the butter. Keep stirring till the butter doesn’t readjust any more.

Note: tell students that while they warmth the butter and stir it, you will stir the exact same amount that butter in the same form of cup yet not heat it. Explain that you want to watch if anything happens to the butter from simply stirring it, or if it’s the warm that really causes the melting.

Ask students:What did friend see happen to the butter?It melted and also became a liquid.How walk you recognize it to be a liquid?When us tilted the cup, the butter flowed.

Note: let students know that the butter you stirred without heater didn’t change much in ~ all. The readjust must have actually been led to by the heat and also not just the stirring.

3. Have students inspection what happens as soon as the liquid butter is cooled.


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Ask Students:Do you think the liquid butter would gain hard again if girlfriend cooled it?Take the cup the end of the warm water and place that in the cup of ice water. Do not stir the liquid butter this time.Keep the cup in the ice cream water and gently touch the butter with your Popsicle stick. If the butter seems hard, scrape part up with the Popsicle stick.Ask students:What do you notification after the butter is in the cold water because that a couple of minutes?It is tough again.

EXPLAIN

4. Present an computer animation to describe that heating makes things relocate faster and come apart and also cooling renders things move slower and also connect together.


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Show the animation Heating and also Cooling.

Explain the the butter is comprised of molecule of fat. Once the butter is solid, the molecules are close together and also do not relocate past every other. When the butter is heated, the molecules begin to move and also are able to slide previous each other and become a liquid. When the fluid butter is cooled, the molecules slow-moving down and also reconnect to become a solid again.


EXTEND

5. Display time slide out videos of ice cream melting.

Ask students:What alters happen if you heat ice cream? The ice cream turns into a difficult liquid.

Show the video Melting ice cream Cream Bar.

See more: What Type Of Experiment Is One Way To Test A Hypothesis ? Controlled Experiments (Article)

Ask students:Could the liquid from the melted ice cream cream bar be put in the freezer to make ice cream again? Yes. Explain that warming ice cream renders it readjust to a liquid, but the liquid can be cooled and readjusted back come solid ice cream cream again. The lightly of the ice cream normally changes due to the fact that the refrozen ice cream cream does not have as much air mixed in with it.

As an extra extension, you can show college student an animation around how ice cream cream is made from Secret science of ingredient – ice cream cream.