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That"s A N(ice) Temperature

Overview

In this 30-minute companion task to The Melting Point, teams of kids periods 8 to 13 experiment to find the melting and also 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 characteristics of a substance. They perform not adjust. Physical properties encompass color, smell, freezing/melting point, and thickness. The freezing allude of water is the very same as the melting allude 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 read, preferably in both Celsius and also Fahrenheit, and that is safe for use by kids 1 (7-ounce) cup or larger plastic container 1 (8-ounce) clear plastic cup Enough foil to cover the peak — however not the sides — of the cup ~5 cups of ice cubes (not crushed ice) (Make sure the ice cubes are loose and also not stuck together.) 1 cup of crushed ice ~2 cups of rock salt (the sort supplied to make ice cream) 1 timer, stopwatch, watch, or clock with a 2nd hand Paper Towels

For the facilitator:

A permanent marker 2 task set-ups to use for demonstration objectives (One will be the same to the children"s, the various other will certainly include all actions but salt will certainly be omitted.)

Preparation

Check the thermometers to ensure that they are working. Prepare the activity set-ups you will use for demonstration throughout the task.

Activity

Introduce the activity by stating the freezing temperatures of water and also the melting temperatures of ice. At what temperature does water freeze? 32°F (0°C). Ask them around their experiences with ice. Wright here carry out they uncover it? In their freezers. How cold is the freezer? Have they ever before observed ice freezing outside? What was the temperature? The youngsters may not recognize the numerical answer, yet they will certainly uncover it in the task. Explain to the kids that this is referred to as the "Freezing Point" of water. Ask the youngsters to make predictions about the melting point of ice. At what temperature execute they think ice melts? Aobtain, the kids may or may not understand. Invite the kids to think around their experiences. Would ice melt on a hot summer day outside in the Sun? What might that heat external 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 deserve to cause water to change state, and also these transforms happen at certain temperatures. Fresh water transitions between the solid and also liquid says at 32°F (0°C) at sea level. At temperatures 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 also changes state from a solid to a liquid (water); 32°F (0°C) is the melting point. For most substances, the melting and freezing points are about the same temperature.
Share with the children that they are about to undertake some experiments to determine the freezing suggest of water and the melting suggest of ice. Can they come up via some ideas for an experiment to find this information? Divide the children right into groups of 4 to 6 and provide them through their Ice Investigator Journals, the cups of cruburned ice, thermometers, pencils or pens, and paper towels. Prompt them to place the thermometer so that the bulb is sitting in the middle of the cup of ice, toward the bottom. It is necessary that the thermometer does not touch the sides or bottom of the cup and also that the ice is tightly packed in the cup. Invite the children to document their predictions in their Ice Investigator Journals. After the thermometer has actually been in the ice for a few minutes, the children can attempt to get a temperature of their ice. The readings they collect may be cshed to 32°F (0°C), however may vary for a number of reasons. The warmer air in the room have the right to circulate in the air pockets between the pieces of crushed ice, bring about their readings to be warmer. Warmer readings may also aincrease bereason the thermometer was in contact through the sides or bottom of the cup, or it wasn"t buried deeply sufficient in the ice, or the kids may have actually held it out of the ice for also long before analysis it. Colder analysis might happen because traditional family members freezers are primarily kept at about 0°F (-18°C) and also the ice will also be that cold. In enhancement, some thermometers review in a different way. Remind them that 32° Fahrenheit is the very same temperature as 0° Celsius. They are just two names for the very same temperature on different temperature scales. Scientists use the Celsius range. Allow the ice to melt for 5 to 10 minutes. Have the kids collect a temperature reading as soon as tbelow is enough water to immerse the thermometer bulb in the water. Invite each team to share the temperature readings from the water. What readings did they find? The readings must be pretty close to 32°F (0°C). Were they all similar? What does this tell us around the temperature at which ice melts — or the melting allude of ice? It 32°F (0°C).Share with the kids that the temperature at which ice melts is dubbed the melting allude. The melting allude is the temperature at which a solid transforms to a liquid. The melting suggest at which ice — a solid transforms to water — a liquid — is 32°F (0°C). Invite the kids to document their responses in their Ice Investigator Journals. If tright here is time, enable the ice to melt for one more 5 to 10 minutes. What perform the youngsters think the temperature will certainly be? Some of the kids may voice that the temperature will be warmer as even more ice has actually melted. Have the youngsters take one more temperature reading. What perform they find? The temperature is still the very same as the original reading, about 32°F (0°C). The temperature will certainly reprimary at 32°F (0°C) till all the ice is melted. Once the ice is melted, the temperature of the water will warm until it reaches the temperature of the room
Facilitator"s Note: Contrary to our instincts, the melt water"s temperature will certainly not rise as long as ice is existing. The heat room continues to include energy to the cup, yet every one of that energy proceeds to go right into melting the ice fairly than raising the temperature. Once all the ice has melted, that energy can begin to rise the water"s temperature.
Ask the children exactly how they could re-freeze the melted water without placing the cup earlier into the freezer. Is there somepoint they can carry out, based upon what they learned in the Melting Point Activity? Do all substances have actually the same melting point?Invite the youngsters to record their responses in their Ice Investigator Journals. Provide the children through the larger container, ice cubes, foil, and salt. Demonstprice the various measures of the experiment and have the youngsters repeat what you do. Cover the entire bottom of the large container via 1/3 of the ice cubes. Cover the height of the cup that has crushed ice and water from the previous experiments with foil. Place it in the middle of the container on optimal of the ice. Sprinkle fifty percent 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 staying 1/3 of the ice cubes. Make sure that the height of the cup with crumelted ice is a small above the layers of ice and also salt.Remove the foil from the cup, area the lid on the container, and enable the experiment to sit undisturbed for about 10 minutes. As the facilitator, repeat the experimental style for one additional container, yet leave out the salt. This container will certainly host only ice cubes and also the cup of cruburned ice and also melt. Share what you are doing with the youngsters. Invite the kids to predict what will occur to the cups of cruburned ice that are in the containers of salt and ice. Will the crushed ice proceed to melt? Will it sheight melting? Will it freeze? What will occur to the cup of crushed ice in the huge container that does not have any salt?
Facilitator"s Note: Adding salt lowers the melting point of water. Pure water and ice, retained insulated from the warmth external people, concerned equilibrium over time. On a molecular level, water molecules are freezing onto the ice at the very same price as they are melting off of it. The whole water/ice solution is at the melting/freezing suggest, 32°F (0°C). Adding rock salt or any kind of substance that dissolves in water disrupts this equilibrium. Fewer water molecules are interacting via the ice at any offered moment, so the freezing price is slowed. The salt has no result on the melting rate, so more melting occurs than freezing — melting "wins" and the ice melts. In doing so, warm power is provided to break the hydrogen bonds that hold the molecules in the ice together. In other words, the ice "supplies up" some warmth from the solution and the temperature drops. Melting and freezing aget enhance rates ("tie") when the temperature has dropped to the brand-new melting allude. The better the amount of salt, the reduced the freezing point (to a point; when tright here is enough salt that no even more will certainly disfix, the freezing allude no longer decreases). Ocean water is around 3.5% salt; sea water freezes at around 28°F (-2°C). A 10% salt solution freezes at about 20°F (-6°C), and also 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 actually already completed the companion task, The Melting Point, remind them of their experiences with the salt on the ice cubes. After 5 to 10 minutes, inspect to view if the predictions were correct! Keep in mind that the experiment should be stopped 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 youngsters observe about the water that had remained in the bottom of their cup of cruburned ice? Several of it has frozen (again).Have the kids take an additional temperature analysis of the staying water. What do they find? The water temperature is 32°F (0°C). If some of the water has actually frozen, what does this intend that the freezing allude of water is? 32°F (0°C). Share the results from the container of ice without salt. What do the youngsters observe about the water in the bottom of the cup of crumelted ice? It is not frozen. More might have melted. Why did melted ice in the ice/salt mixtures refreeze and also the melted ice in the other container not? Since the temperature of the ice/salt mixture was cold enough to refreeze the water. Invite them to discover the temperature of the ice/salt mixture utilizing one of their thermometers. At the same time, have them take the temperature of the crushed ice aget. What carry out they find? The temperature of the ice/salt mixture is reduced than 32°F (0°C); it may be as low as 0°F (-18°C). Note, the temperature will certainly differ, depending upon exactly how much salt is offered, exactly how well the salt dissolves, and also the temperature of your freezer. Have the children proceed to make notes about their findings in their Ice Investigator Journals. Discuss their speculative findings. At what temperature does fresh water turn to ice? 32°F (0°C). Share that the temperature at which fresh water freezes is dubbed the freezing allude. The freezing allude is the temperature at which a liquid turns to a solid. The freezing allude at which water — a liquid — turns 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 allude of ice? 32°F (0°C). How deserve to the melting and freezing temperatures be the same? The melting suggest and also freezing suggest are the same temperature for any specific substance: 32°F (0°C) for water. This temperature is described as the melting point when temperatures rise above 32°F (0°C), leading to ice to melt and also readjust state from a solid to a liquid (water), as happened through the cup of crushed ice at room temperature. It is referred to as the freezing allude once temperatures decrease below 32°F (0°C), bring about water to adjust state from a liquid to a solid (ice), as happened with the cup of crushed ice immersed in the extremely cold salt/ice mixture. Why is the ice/salt mixture colder? Salt lowers the freezing point of water. Salty water stays liquid at lower temperatures — or freezes at a chillier temperature — than fresh water.

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Conclusion

If the kids have actually began to construct a snow mobile, invite them to document any kind of answers they found on the appropriate pieces. A few of the inquiries that they ca response could 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 renders __________.

Have them annotate any new inquiries they have or exciting things they learned on the appropriate forms of either raindrop, cloud, or snowflake.