One of the first things you learn when you do science is that experiments don’t always turn out the way you hope they will. And that’s OK. If at first you don’t succeed….
We tried to measure how far a sneeze would throw visible droplets by putting grape juice in our mouths and tickling our noses with feathers dipped in pepper. Sadly, no matter how hard we tried, we couldn’t seem to sneeze with grape juice in our mouths. Laughing so hard we spit the juice out was one unexpected outcome. We decided to try it again in the future using petri dishes spaced at intervals to avoid the grape juice problem.
Since there was no school today and it was ten degrees below zero (F), we tried throwing boiling water into the air to see if it would freeze before it hit the ground. Once again, our experimental conditions were less than perfect, and although some of the water froze into an icy cloud, the majority hit the ground with a splash. The experiment would have worked better at -20F, but it was still fun!
Salt lowers the melting/freezing temperature of ice, which is the solid form of water. Here’s a fun experiment you can do to see for yourself how Sodium Chloride (table salt) makes ice melt and water refreeze on a string, allowing you to “magically” lift an ice cube from a glass of water.
Click here for detailed instructions and more about the science.
This video will soon appear on KidScience app‘s Premium version, which allows you to easily search for experiments and videos based on kids’ ages, type of science, what you have on hand, or how much time you have.
Have you ever wondered why putting chemicals on a road makes the ice melt? Here in Anarctica, I mean Minnesota, there have been lots of trucks out spreading de-icer lately.
You can see how one of these chemicals: NaCl, or table salt helps melt ice by lowering the melting temperature of water for yourself. All you’ll need is an ice cube, a glass of water, a piece of kitchen twine or string about 6 inches long and salt.
Drop an ice cube in a glass of ice water. Try to pick the ice cube up without your fingers by simply placing the string on it and pulling up. Impossible, right?
Now, dip the string in water, lay it across the ice cube and sprinkle a generous amount of salt over the string/ice cube. Wait about a minute and try again to lift the cube using only the string. What happens?
It may seem like magic, but it’s only science. I demonstrated how do do this experiment on Kare11 news the other day. It’s right after the static electricity experiment. Here’s a video from my KidScience app where I demonstrate the experiment.
Salt lowers the temperature at which ice can melt and water can freeze. Usually, ice melts and water freezes at 32 degrees Farenheit, but if you add salt to it, ice will melt at a lower (colder) temperature.
The salt helps the ice surrounding the string start to melt, and it takes heat from the surrounding water, which then re-freezes around the string.
Different chemicals change the freezing point of water differently. Salt can thaw ice at 15 degrees F, but at 0 degrees F, it won’t do anything. Other de-icing chemicals they add to roads can work at much colder temperatures (down to 20 degrees below zero.) If it’s cold enough, even chemicals won’t melt the ice.
Pressure can also make ice melt at colder temperatures. This is why ice skates glide on rinks. The pressure is constantly melting the ice a where the blade presses down on it so the blade glides on a thin layer of water!
We were up at the lake last week when the ice went out. It was amazing. We arrived at noon to a lake whose surface was half covered with ice and woke the next morning to clear water. The wind was blowing the ice into shore and it broke into millions of crystals that sounded like a field of windchimes. The crystals were so sharp that our dog cut his foot.
If you’re interested, you can watch the very wobbly, but cool video I took of the ice blowing around. You can see the ice crystals being pushed up and out of the water into piles. Listen, and you’ll hear the ice crystals clinking together!
This week, the kids and I are going to grow alum and sugar crystals, so be sure to check for the upcoming post!