Have you ever wondered how much water is in snow or why sprinkling salt on walkways and roads helps ice melt away? January is a cold month for many of us, but even if there isn’t any snow where you live, you can still experiment with ice!
What happens when snow melts? If you walk outside on a snowy day, your shoes or boots will likely have some snow on them when you come inside. After a few minutes, the snow will become nothing more than a puddle of water on the floor beneath your shoes!
Snow is made when water freezes in the form of ice crystals that we call snowflakes. Snow and ice begin to melt at 32 degrees Fahrenheit. When you brought the container full of snow inside, some of it began to melt almost immediately, although you may not have noticed any melting happening until later on when you started to notice water in the container, too!
When we tried this experiment, our container started out with 16 cm of snow. After all the snow had melted, the container only had 2.5 cm of melted snow (water)! We expected a little more water than that - how about you? (Note: Results from this experiment can vary from one location or one snowfall to another. Sometimes snow is dry, meaning the snowflakes don’t have much moisture in them; other times snow is wet with more moisture in the snowflakes. Humid climates often get wet snow while dry, mountainous areas tend to get drier snowfalls.)
How is it possible for snowflakes to fill the container completely but for the same amount of snow to melt into only a small amount of water? The pointed star-like shape of a snowflake causes it to take up a lot of room because its points stick out far from its body. Think about it like this: if you stick your arms straight out from your body, your arms would cause your body to take up more space and you may find yourself bumping into walls or having a hard time making your way down a hallway. Something similar happens when lots of snowflakes pile up. The points from all of the snowflakes keep them from getting very close together, creating empty space in between them. When the snow melts into water, the snowflakes no longer have their points, and the space between them is gone. If you put your arms down next to your body, you are no longer taking up so much space and can get much closer to other people and things.
You may have noticed people sprinkling chunks of salt on the sidewalks or roads during the winter to help melt ice. Learn why salt melts ice in this cool experiment.
As we discovered in the snow experiment, water freezes and ice and snow melt at 32 degrees Fahrenheit. This is known as the freezing point of water. Salt (scientific name: sodium chloride) lowers the freezing point of water. When that happens, ice will melt at a lower temperature than normal. That’s exactly what happened in this experiment.
When you poured salt on top of the ice cubes in the glass of water, they started to melt almost instantly because the salt lowered the freezing point of the ice. In other words, once you added the salt, the glass would have had to get a lot colder to keep the ice frozen since salt makes ice melt at a lower temperature. Some of the ice around the string started to melt almost immediately. However, after a few minutes, the small amount of salt you added began to be dissolved into the water around the ice, which caused the freezing point on the surface of the ice to go back to normal. When that happened, some of the water re-froze around the ice, freezing the string to it, too!
Play with salt and ice some more with this pretty project.
As we discussed in the previous experiment, table salt lowers the freezing point of water. In this case, it means the salt makes the ice start to melt almost right away. Adding colors on top of the salted ice allowed you to see the effect salt had on the ice a little better. Notice how the salt formed cracks and holes down the sides of the ice chunk and made the top part seem a little slushy? If you’d like, you can add more salt to some of the ice and check back periodically to see which ice melts faster—the one with just a little salt, or the one with more salt?
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