We are going to take a little detour from invertebrates, because I have an awesome party trick for you!
Are you tired of the same old party tricks? Pulling a rabbit out of a hat? Pff been done. ‘Sawing’ someone in half only to have them magically be whole one minute later? Old news! I’ve got something better. Imagine, if you will, you are at a party, and their ice cube stock is getting dangerously low, and they don’t have an ice cube tray in sight (bonus points if it’s the middle of summer and scorching hot out). The fridge is so full of party food that none of the cola or other beverages can fit. Sure, you could run to the store and buy another bag of ice, or you could be the supercool hero of the day and create instant ice before your friends’ eyes!Now, by instant ice, what I really mean is, place a sealed plastic water bottle in the freezer, wait about 2.5 hours, then pull out the bottle (noting it is still liquid inside), open it carefully and slowly pour it onto a chilled dish, at which point it will turn to ice, INSTANTLY! Really the instant part takes place at the end and it takes a bit of prep time, but all things worth doing take a little time right? So worth it for this result:
What you are seeing in the photo to the left is supercooled water instantly freezing when poured onto a chilled dish. Liquid to solid, in a blink of the eye. Supercooling means the liquid is below the normal temperature of freezing, which is 0°C for pure water, yet it remains in liquid form. How is this possible? Ice is able to form when the molecules within a liquid align just right and bond tightly together, forming ice crystals. Once you have one ice crystal, a chain reaction occurs where other ice crystals can form next to the original one, and this continues until all the liquid has frozen into a solid state. If that first ice crystal never forms, the liquid will remain in a liquid state despite being below the normal freezing temperature. This is called supercooling, which can occur down to -40°C! There are a few different things that can help that first ice crystal form, including minerals or other impurities in the liquid. This is why filtered, bottled water works best for this trick, because if you used tap water, there are more impurities present, and therefore more opportunities for the first ice crystal to form while in the freezer, leading to the whole bottle of water freezing before you even bring it out of the freezer. If, however, you use filtered water, there is a much better chance an ice crystal won’t form while in the freezer, which allows the water to still be liquid when you take it out of the freezer. Then when you carefully open the bottle, and pour it onto a chilled dish (one that was also in the freezer), the movement of the water during the pouring action jostles the molecules and allows ice crystals to form, creating ice when it hits the chilled dish. Cue awe from your friends!
If you aren’t careful when you pull the bottle of water out of the freezer, and you hit it on something, this could cause ice crystals to form inside the bottle before you open it. If that happens, you will see a cascade of ice forming from the top of the bottle down to the bottle, like in the photo to the left. Which would be pretty neat to watch in itself, but less useful for keeping party drinks cool.
This trick can also be done with sealed bottles of pop, or other beverages. Just make sure not to use glass containers for the liquid, just in case the bottle does fully freeze and expands to break the glass. You don’t want that mess.
Recap: Science rules! And is useful! And awe inspiring. On another note, considering this is a biology blog you might be wondering why I haven’t mentioned anything about animals. Well there are animals that can supercool themselves! That’s right, they produce antifreeze proteins that prevent ice crystals forming in their body, which allows them to become supercooled just like our bottle of water. Seems crazy right? But it’s true, and you can read some of my fellow classmate’s blogs about this or follow the links below to find out more!
Antifreeze proteins: http://www.nytimes.com/2010/01/19/science/19creatures.html?_r=0
Freeze avoidance and tolerance: http://www.nwf.org/news-and-magazines/national-wildlife/animals/archives/2011/animals-getting-through-winter.aspx
Video on supercooling water: https://www.youtube.com/watch?v=NMSxuORKynI