All About Ice

That's A N(ice) Temperature

Overview

In this thirty-minute companion activity to The Melting Bespeak, teams of children ages viii to thirteen experiment to observe the melting and freezing points of water and ice.

What'southward the Point?

  • Water can exist in unlike states; ice is the solid state of water.
  • Concrete properties are characteristics of a substance. They do not alter. Physical properties include color, scent, freezing/melting point, and density.
  • The freezing indicate of water is the same as the melting point of ice: 32°F (0°C).

Materials

For each child

  • His/her Water ice Investigator Journal
  • His/her envelope of mobile pieces
  • Pencil or pen

For each grouping of four to 6 children:

  • i thermometer that is easily read, preferably in both Celsius and Fahrenheit, and that is safe for utilize past children
  • ane (seven-ounce) cup or larger plastic container
  • ane (eight-ounce) clear plastic loving cup
  • Enough foil to cover the top — but not the sides — of the cup
  • ~5 cups of ice cubes ( not crushed ice) (Make sure the water ice cubes are loose and not stuck together.)
  • 1 cup of crushed ice
  • ~2 cups of rock salt (the kind used to make water ice cream)
  • 1 timer, stopwatch, watch, or clock with a second hand
  • Paper Towels

For the facilitator:

  • A permanent marker
  • two activity set-ups to utilise for sit-in purposes (One volition be identical to the children's, the other will include all steps but salt will be omitted.)
  • Background information

Preparation

  • Cheque the thermometers to ensure that they are working.
  • Prepare the activity set-ups you will utilize for demonstration during the action.

Activity

  1. Innovate the activity by discussing the freezing temperatures of water and the melting temperatures of ice.
    • At what temperature does h2o freeze? 32°F (0°C). Ask them about their experiences with ice. Where practise they find information technology? In their freezers. How cold is the freezer? Have they always observed water ice freezing outside? What was the temperature? The children may not know the numerical answer, just they volition discover information technology in the activity. Explain to the children that this is called the "Freezing Betoken" of water.
    Ask the children to make predictions nigh the melting point of ice.
    • At what temperature do they think ice melts? Again, the children may or may non know. Invite the children to think most their experiences. Would ice cook on a hot summertime solar day exterior in the Sun? What might that warm outside temperature be? Would it cook in the room in which the children are at this moment? Probably (hopefully!). What is the temperature of the room?

    Facilitator's Annotation: Changes in temperature tin crusade water to modify state, and these changes occur at specific temperatures. Fresh water transitions between the solid and liquid states 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 signal of h2o. At temperatures above 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 well-nigh substances, the melting and freezing points are well-nigh the aforementioned temperature.

    Share with the children that they are about to undertake some experiments to decide the freezing point of water and the melting point of ice. Can they come up with some ideas for an experiment to find this information?
  2. Divide the children into groups of four to six and provide them with their Water ice Investigator Journals, the cups of crushed ice, thermometers, pencils or pens, and paper towels.
  3. Prompt them to identify the thermometer so that the bulb is sitting in the middle of the cup of water ice, toward the bottom. Information technology is important that the thermometer does not touch the sides or bottom of the loving cup and that the ice is tightly packed in the loving cup.

    Invite the children to record their predictions in their Water ice Investigator Journals.

    Afterward the thermometer has been in the water ice for a few minutes, the children tin can attempt to get a temperature of their ice. The readings they collect may be shut to 32°F (0°C), but may vary for several reasons. The warmer air in the room tin circulate in the air pockets between the pieces of crushed ice, causing their readings to exist warmer. Warmer readings may also arise because the thermometer was in contact with the sides or lesser of the cup, or it wasn't cached securely enough in the water ice, or the children may take held information technology out of the ice for too long before reading it. Colder reading may occur because standard household freezers are by and large kept at about 0°F (-18°C) and the ice volition besides be that common cold. In improver, some thermometers read differently.

    Remind them that 32° Fahrenheit is the same temperature as 0° Celsius. They are only two names for the aforementioned temperature on unlike temperature scales. Scientists utilize the Celsius scale.

  4. Allow the ice to melt for 5 to ten minutes. Have the children collect a temperature reading once there is sufficient water to immerse the thermometer seedling in the water.
  5. Invite each team to share the temperature readings from the water.
    • What readings did they observe? The readings should be pretty shut to 32°F (0°C).
    • Were they all similar? What does this tell usa about the temperature at which ice melts — or the melting point of water ice? It 32°F (0°C).
    Share with the children that the temperature at which ice melts is called the melting point. The melting point is the temperature at which a solid turns to a liquid. The melting indicate at which ice — a solid — turns to water — a liquid — is 32°F (0°C). Invite the children to record their responses in their Ice Investigator Journals.
  6. If there is fourth dimension, let the water ice to cook for another 5 to ten minutes.
    • What do the children think the temperature will be? Some of the children may voice that the temperature will be warmer equally more ice has melted.
  7. Have the children take some other temperature reading.
    • What do they find? The temperature is still the same as the original reading, about 32°F (0°C). The temperature volition remain at 32°F (0°C) until all the ice is melted. Once the ice is melted, the temperature of the water will warm until information technology reaches the temperature of the room

    Facilitator'due south Note: Reverse to our instincts, the melt water's temperature will not increase every bit long as ice is present.  The warm room continues to add energy to the loving cup, but all of that free energy continues to go into melting the water ice rather than raising the temperature.  Once all the ice has melted, that free energy tin can begin to increment the water's temperature.

    • Ask the children how they might re-freeze the melted water without putting the cup back into the freezer.
    • Is in that location something they can do, based on what they learned in the Melting Indicate Activeness?
    • Exercise all substances have the aforementioned melting point?
    Invite the children to record their responses in their Ice Investigator Journals.
  8. Provide the children with the larger container, ice cubes, foil, and common salt. Demonstrate the different steps of the experiment and accept the children repeat what you practice.
    • Cover the entire bottom of the large container with 1/3 of the ice cubes.
    • Embrace the top of the loving cup that contains crushed ice and water from the previous experiments with foil. Place information technology in the middle of the container on top of the ice.
    • Sprinkle half of the table salt over the water ice cubes. Create another layer of ice over the salt using 1/3 of the ice cubes. Sprinkle this layer with the rest of the salt. Comprehend it with the remaining one/three of the water ice cubes. Brand sure that the peak of the cup with crushed ice is a fiddling higher up the layers of ice and salt.
    Remove the foil from the cup, place the chapeau on the container, and allow the experiment to sit undisturbed for virtually ten minutes.
  9. As the facilitator, repeat the experimental pattern for one boosted container, merely leave out the salt. This container will hold only ice cubes and the loving cup of crushed ice and cook. Share what you are doing with the children.
  10. Invite the children to predict what will happen to the cups of crushed ice that are in the containers of salt and water ice.
    • Will the crushed ice continue to melt?
    • Will it terminate melting?
    • Will it freeze?
    • What volition happen to the cup of crushed ice in the large container that does not take any common salt?

    Facilitator's Notation: Adding salt lowers the melting indicate of water.

    Pure water and ice, kept insulated from the warm exterior world, come to equilibrium over time. On a molecular level, water molecules are freezing onto the water ice at the same charge per unit equally they are melting off of it. The entire water/ice solution is at the melting/freezing signal, 32°F (0°C). Calculation stone salt — or any substance that dissolves in water — disrupts this equilibrium. Fewer h2o molecules are interacting with the ice at any given moment, then the freezing rate is slowed. The table salt has no consequence on the melting rate, so more melting occurs than freezing — melting "wins" — and the ice melts. In doing so, heat free energy is used to break the hydrogen bonds that hold the molecules in the ice together. In other words, the water ice "uses upwards" some warmth from the solution and the temperature drops. Melting and freezing over again friction match rates ("tie") once the temperature has dropped to the new melting point.

    The greater the corporeality of salt, the lower the freezing bespeak (to a point; once there is sufficient table salt that no more will deliquesce, the freezing point no longer decreases). Ocean h2o is nearly three.5% salt; bounding main water freezes at about 28°F (-two°C). A 10% salt solution freezes at nigh xx°F (-6°C), and a 20% solution freezes at two°F (-xvi°C).

    Prompt the children to brainstorm why they recollect their predictions will exist right.If you have already completed the companion activity, The Melting Signal, remind them of their experiences with the table salt on the ice cubes.
  11. After five to 10 minutes, check to see if the predictions were correct! Note that the experiment should be stopped when some of the water has refrozen, not all. Have the children uncover their containers and lift the cup of crushed ice out of the bowl.
    • What do the children detect most the water that had been in the bottom of their loving cup of crushed ice? Some of it has frozen (again).
    Have the children take another temperature reading of the remaining h2o.
    • What exercise they observe? The h2o temperature is 32°F (0°C).
      • If some of the water has frozen, what does this mean that the freezing point of water is? 32°F (0°C).
  12. Share the results from the container of ice without salt.
    • What do the children observe about the water in the bottom of the loving cup of crushed ice? It is not frozen. More may have melted.
    • Why did melted ice in the water ice/salt mixtures refreeze and the melted ice in the other container non? Because the temperature of the water ice/salt mixture was common cold enough to refreeze the water.
  13. Invite them to find the temperature of the ice/salt mixture using ane of their thermometers. At the same time, have them take the temperature of the crushed ice again.
    • What practise they find? The temperature of the water ice/table salt mixture is lower than 32°F (0°C); it may be equally depression as 0°F (-18°C). Annotation, the temperature will vary, depending on how much salt is used, how well the common salt dissolves, and the temperature of your freezer.
    Have the children go along to make notes about their findings in their Ice Investigator Journals.
  14. Discuss their experimental findings.
    • At what temperature does fresh water turn to ice? 32°F (0°C). Share that the temperature at which fresh h2o freezes is chosen the freezing betoken. The freezing point is the temperature at which a liquid turns to a solid. The freezing point at which water — a liquid — turns to ice — a solid — is 32°F (0°C).
    • Based on their experiments melting the crushed ice, at what temperature does ice cook to brand h2o — what is the melting point of ice? 32°F (0°C).
    • How can the melting and freezing temperatures be the aforementioned? The melting point and freezing point are the same temperature for whatsoever particular substance: 32°F (0°C) for water. This temperature is referred to as the melting point when temperatures ascent to a higher place 32°F (0°C) , causing water ice to melt and alter country from a solid to a liquid (water), as happened with the loving cup of crushed water ice at room temperature . Information technology is referred to every bit the freezing point when temperatures decrease beneath 32°F (0°C) , causing h2o to change state from a liquid to a solid (ice), as happened with the cup of crushed ice immersed in the very common cold table salt/water ice mixture .
    • Why is the water ice/common salt mixture colder? Salt lowers the freezing point of water. Salty water stays liquid at lower temperatures — or freezes at a colder temperature — than fresh h2o.

Conclusion

If the children take started to construct a snow mobile, invite them to record any answers they discovered on the appropriate pieces. Some of the questions that they can reply might include:

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

Have them comment whatever new questions they have or interesting things they learned on the appropriate shapes of either raindrop, cloud, or snowflake.