Too much cool stuff
So, my cup runneth over with awesome stuff. Some of which then explodes.
Today we made liquid CO2.
To understand why this is so cool, you need a bit of background. Firstly, in the grand scheme of things, liquids are ...difficult. Matter tends to want to be either a solid or a gas - you need just the right combination of temperature and pressure to make liquid happen. This may seem strange, because we live on a planet covered with the stuff, but on a universal scale, liquids are actually extremely rare.
Carbon dioxide is found naturally in one state on the Earth: gas. It's possible to produce it in solid form, which we call Dry Ice (or alternatively Hot Ice, since it can burn you). While Dry Ice doesn't occur naturally on earth, the Martian ice caps are composed of it. Mars is like the CO2 capital of the solar system.
The cool thing about Dry Ice is that it sublimates rather than melts. Unlike most substances, CO2 passes directly from a solid to a gas without ever becoming liquid. Other gasses (such as nitrogen and oxygen) we can get in liquid form simply by getting them cold enough - but not so CO2. This is why, while Dry Ice is fairly easy to come by (and awesome for Halloween decorations), most people will never see liquid CO2 in their lives.
So, here's how we did it. For CO2 to exist as a liquid, it needs to be under at least 5 ATMs of pressure. A good way to get pressure is the expansion of gas. So.
Take some dry ice. Mash it up really well.
Cut a plastic pipette in half and scoop your mashed up dry ice into the big end.
Fold over and close up the cut end with a pair of pliers.
Lower the bulb end with the dry ice into a beaker of warm water.
The warm water will cause the dry ice to sublimate, but since volume is fixed, the rapidly expanding gasses will build up pressure inside the pipette, which will force the remaining dry ice into liquid form.
At which point you'll have about two seconds before it explodes, sending your warm water everywhere.
Interestingly, as soon as the pressure is released, the non-sublimated CO2 will immediately re-form into a solid, so you are likely to end up with bigger pieces of dry ice than you started with.
This was my day today. How was yours?
Today we made liquid CO2.
To understand why this is so cool, you need a bit of background. Firstly, in the grand scheme of things, liquids are ...difficult. Matter tends to want to be either a solid or a gas - you need just the right combination of temperature and pressure to make liquid happen. This may seem strange, because we live on a planet covered with the stuff, but on a universal scale, liquids are actually extremely rare.
Carbon dioxide is found naturally in one state on the Earth: gas. It's possible to produce it in solid form, which we call Dry Ice (or alternatively Hot Ice, since it can burn you). While Dry Ice doesn't occur naturally on earth, the Martian ice caps are composed of it. Mars is like the CO2 capital of the solar system.
The cool thing about Dry Ice is that it sublimates rather than melts. Unlike most substances, CO2 passes directly from a solid to a gas without ever becoming liquid. Other gasses (such as nitrogen and oxygen) we can get in liquid form simply by getting them cold enough - but not so CO2. This is why, while Dry Ice is fairly easy to come by (and awesome for Halloween decorations), most people will never see liquid CO2 in their lives.
So, here's how we did it. For CO2 to exist as a liquid, it needs to be under at least 5 ATMs of pressure. A good way to get pressure is the expansion of gas. So.
Take some dry ice. Mash it up really well.
Cut a plastic pipette in half and scoop your mashed up dry ice into the big end.
Fold over and close up the cut end with a pair of pliers.
Lower the bulb end with the dry ice into a beaker of warm water.
The warm water will cause the dry ice to sublimate, but since volume is fixed, the rapidly expanding gasses will build up pressure inside the pipette, which will force the remaining dry ice into liquid form.
At which point you'll have about two seconds before it explodes, sending your warm water everywhere.
Interestingly, as soon as the pressure is released, the non-sublimated CO2 will immediately re-form into a solid, so you are likely to end up with bigger pieces of dry ice than you started with.
This was my day today. How was yours?