## That"s A N(ice) Temperature

### Overview

In this 30-minute companion task to The Melting Point, groups of youngsters ages 8 to 13 experiment to discover the melting and freezing points of water and also ice.

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### What"s the Point?

Water deserve to exist in different states; ice is the solid state of water. Physical properties are attributes of a substance. They do not change. Physical properties incorporate color, smell, freezing/melting suggest, and density. The freezing allude of water is the exact same as the melting suggest of ice: 32°F (0°C).

### Materials

For each child

His/her envelope of mobile pieces Pencil or pen

For each team of 4 to 6 children:

1 thermometer that is conveniently review, preferably in both Celsius and also Fahrenheit, and that is safe for usage by kids 1 (7-ounce) cup or larger plastic container 1 (8-ounce) clear plastic cup Enough foil to cover the top — yet not the sides — of the cup ~5 cups of ice cubes (not crumelted ice) (Make certain the ice cubes are loose and not stuck together.) 1 cup of crushed ice ~2 cups of rock salt (the type used to make ice cream) 1 timer, stopwatch, watch, or clock via a 2nd hand also Paper Towels

For the facilitator:

A irreversible marker 2 activity set-ups to usage for demonstration functions (One will certainly be identical to the children"s, the other will incorporate all procedures but salt will certainly be omitted.)

### Preparation

Check the thermometers to ensure that they are functioning. Prepare the task set-ups you will certainly usage for demonstration during the activity.

### Activity

Introduce the task by stating the freezing temperatures of water and the melting temperatures of ice. At what temperature does water freeze? 32°F (0°C). Ask them about their experiences via ice. Wbelow do they find it? In their freezers. How cold is the freezer? Have they ever oboffered ice freezing outside? What was the temperature? The kids may not understand the numerical answer, yet they will uncover it in the activity. Explain to the youngsters that this is called the "Freezing Point" of water. Ask the kids to make predictions about the melting point of ice. At what temperature perform they think ice melts? Aget, the kids may or may not understand. Invite the youngsters to think about their experiences. Would ice melt on a warm summer day exterior in the Sun? What can that heat exterior temperature be? Would it melt in the room in which the youngsters are at this moment? Probably (hopefully!). What is the temperature of the room?
Facilitator"s Note: Changes in temperature can cause water to change state, and these transforms take place at certain temperatures. Fresh water transitions in between the solid and also liquid claims at 32°F (0°C) at sea level. At temperatures listed below 32°F (0°C), liquid water freezes; 32°F (0°C) is the freezing point of water. At temperatures over 32°F (0°C), pure water ice melts and changes state from a solid to a liquid (water); 32°F (0°C) is the melting point. For a lot of substances, the melting and also freezing points are about the very same temperature.
Facilitator"s Note: Contrary to our instincts, the melt water"s temperature will certainly not increase as long as ice is present. The warm room continues to add energy to the cup, but all of that power continues to go right into melting the ice fairly than increasing the temperature. Once all the ice has melted, that power deserve to start to rise the water"s temperature.
Ask the children just how they could re-freeze the melted water without placing the cup back into the freezer. Is tbelow something they can carry out, based upon what they learned in the Melting Point Activity? Do all substances have the same melting point?Invite the kids to record their responses in their Ice Investigator Journals. Provide the children with the larger container, ice cubes, foil, and salt. Demonstprice the various measures of the experiment and have actually the children repeat what you execute. Cover the entire bottom of the huge container with 1/3 of the ice cubes. Cover the height of the cup that consists of crumelted ice and water from the previous experiments through foil. Place it in the middle of the container on peak of the ice. Sprinkle half of the salt over the ice cubes. Create an additional layer of ice over the salt utilizing 1/3 of the ice cubes. Sprinkle this layer via the rest of the salt. Cover it with the continuing to be 1/3 of the ice cubes. Make sure that the height of the cup through cruburned ice is a small over the layers of ice and also salt.Rerelocate the foil from the cup, area the lid on the container, and also permit the experiment to sit undisturbed for around 10 minutes. As the facilitator, repeat the speculative style for one extra container, however leave out the salt. This container will certainly hold just ice cubes and also the cup of cruburned ice and also melt. Share what you are doing through the youngsters. Invite the kids to predict what will happen to the cups of crumelted ice that are in the containers of salt and ice. Will the crumelted ice proceed to melt? Will it soptimal melting? Will it freeze? What will happen to the cup of crumelted ice in the large container that does not have actually any salt?
Facilitator"s Note: Adding salt lowers the melting allude of water. Pure water and ice, preserved insulated from the warmth exterior civilization, concerned equilibrium over time. On a molecular level, water molecules are freezing onto the ice at the same price as they are melting off of it. The whole water/ice solution is at the melting/freezing point, 32°F (0°C). Adding rock salt or any type of substance that dissolves in water disrupts this equilibrium. Fewer water molecules are communicating through the ice at any kind of offered moment, so the freezing price is slowed. The salt has actually no impact on the melting price, so even more melting occurs than freezing — melting "wins" and also the ice melts. In doing so, warmth power is provided to break the hydrogen bonds that hold the molecules in the ice together. In various other words, the ice "uses up" some warmth from the solution and the temperature drops. Melting and also freezing aobtain enhance prices ("tie") once the temperature has actually dropped to the new melting point. The higher the amount of salt, the reduced the freezing allude (to a point; as soon as tright here is adequate salt that no more will certainly dissettle, the freezing point no longer decreases). Ocean water is around 3.5% salt; sea water freezes at about 28°F (-2°C). A 10% salt solution freezes at about 20°F (-6°C), and a 20% solution freezes at 2°F (-16°C).
Prompt the kids to brainstorm why they think their predictions will be correct.If you have currently completed the companion task, The Melting Point, remind them of their experiences through the salt on the ice cubes. After 5 to 10 minutes, inspect to watch if the predictions were correct! Note that the experiment should be quit when some of the water has refrozen, not all. Have the youngsters uncover their containers and also lift the cup of crushed ice out of the bowl. What execute the kids observe about the water that had actually been in the bottom of their cup of crumelted ice? A few of it has frozen (again).Have the children take another temperature reading of the remaining water. What perform they find? The water temperature is 32°F (0°C). If some of the water has actually frozen, what does this expect that the freezing suggest of water is? 32°F (0°C). Share the outcomes from the container of ice without salt. What perform the children observe about the water in the bottom of the cup of cruburned ice? It is not frozen. More may have actually melted. Why did melted ice in the ice/salt mixtures refreeze and also the melted ice in the other container not? Due to the fact that the temperature of the ice/salt mixture was cold enough to refreeze the water. Invite them to uncover the temperature of the ice/salt mixture utilizing among their thermometers. At the very same time, have actually them take the temperature of the cruburned ice aacquire. What execute they find? The temperature of the ice/salt mixture is reduced than 32°F (0°C); it might be as low as 0°F (-18°C). Note, the temperature will certainly differ, depending upon how much salt is provided, just how well the salt dissolves, and also the temperature of your freezer. Have the youngsters continue to make notes about their findings in their Ice Investigator Journals. Discuss their experimental findings. At what temperature does fresh water revolve to ice? 32°F (0°C). Share that the temperature at which fresh water freezes is called the freezing suggest. The freezing allude is the temperature at which a liquid turns to a solid. The freezing allude at which water — a liquid — transforms to ice — a solid — is 32°F (0°C). Based on their experiments melting the cruburned ice, at what temperature does ice melt to make water what is the melting suggest of ice? 32°F (0°C). How can the melting and also freezing temperatures be the same? The melting point and freezing allude are the very same temperature for any kind of certain substance: 32°F (0°C) for water. This temperature is described as the melting point once temperatures climb above 32°F (0°C), resulting in ice to melt and also readjust state from a solid to a liquid (water), as taken place with the cup of cruburned ice at room temperature. It is referred to as the freezing suggest once temperatures decrease listed below 32°F (0°C), resulting in water to adjust state from a liquid to a solid (ice), as happened through the cup of crushed ice immersed in the very cold salt/ice mixture. Why is the ice/salt mixture colder? Salt lowers the freezing allude of water. Salty water remains liquid at reduced temperatures — or freezes at a colder temperature — than fresh water.

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### Conclusion

If the children have actually began to construct a scurrently mobile, invite them to document any type of answers they found on the proper pieces. Several of the inquiries that they ca response can include:

Water freezes at _________F° / _________C° When water freezes, it turns into__________, which is a solid / liquid / gas. (circle one) Ice melts at _________F° / _________C° When ice melts, it makes __________.

Have them annotate any new questions they have or amazing points they learned on the proper shapes of either raindrop, cloud, or snowflake.