Dry ice is the solid form of carbon dioxide (CO2), just like normal ice is the solid state of water (H.2OR). It is a material extremely cold (-78.5 ° C), so it is used in many industrial fields when you need to cool or freeze something. With the right ingredients, you can even make it at home; you must take the correct security measures and the procedure will be quick and easy.
Steps
Method 1 of 2: With Compressed Carbon Dioxide
Step 1. Get a carbon dioxide fire extinguisher and pillowcase
You only need three items to create dry ice at home: a CO fire extinguisher2, an old fabric pillowcase and a large open space where children and pets can't bother you.
- For this method you need a fire extinguisher specific to CO2 and not one normal for home use. Most of these tools contain fine powders or chemicals, such as sodium or potassium bicarbonate, which cannot replace CO2 needed to produce dry ice.
- CO fire extinguishers2 they are mostly used in laboratories, industrial kitchens and near mechanical instrumentation. They have a black plastic dispenser on the spout and have no pressure gauge.
- You can buy one in hardware stores and also online at specialized retailers.
Step 2. Protect your hands, eyes and limbs
Dry ice is so cold that it causes immediate "freeze burns" if it comes into contact with bare skin. Although a fire extinguisher does not require a protective suit for hazardous materials, you must however take all safety measures to prevent carbon dioxide from dripping or coming into contact with your body. Wear the following clothing:
- Thick, sturdy work gloves (under which you should put another pair of gloves for double protection).
- Safety glasses or laboratory mask.
- Long sleeved shirt and long pants.
- Closed shoes.
- Long-sleeved jacket or lab coat (optional).
Step 3. Wrap the pillowcase tightly around the fire extinguisher hose
Insert the nozzle into the pillowcase and close it tightly behind the plastic dispenser. You must not allow gas to escape from the fabric.
Use strong adhesive tape to seal the opening if you are concerned that the pillowcase may fly off due to the pressure of the fire extinguisher. It shouldn't be a problem to manage the delivery force, but one more precaution doesn't hurt
Step 4. Operate the fire extinguisher
When you are ready, press the handle of the tool and release the gas inside the pillowcase. Maintain the pressure for 2-3 seconds. You may believe that you will not be able to see the ice produced, but it will begin to accumulate on the bottom of the pillowcase. Operate the fire extinguisher for only a few seconds and then release the handle. You will see the carbon dioxide vapors filter through the fabric. This is a normal and completely safe reaction as long as you are in a well-ventilated area.
If you are unable to operate the tool, check that the safety pin that blocks the movement of the handle is not inserted
Step 5. Remove the pillowcase
Detach it carefully from the dispenser. Slide it tightly around the nozzle to eliminate any residual carbon dioxide that has accumulated on it. You should see a small amount of ice inside the pillowcase: it will look similar to that of shredded polystyrene.
Try to keep the pillowcase upright and don't handle the ice more than necessary. You can touch small fragments for a few seconds, but don't grab them for longer or they will freeze your fingers even through the gloves
Step 6. Transfer the dry ice to a safer container
Scratch it from the fabric of the pillowcase and store it in a more suitable container such as a bowl, a sturdy plastic bag, or a portable thermal crate. Try to leave the accumulated fragments so that they last as long as possible. Do not seal the container. If you put an airtight lid, the internal pressure caused by the CO2 that sublime will make him explode. If you decide to use a lid, do not screw it on, do not press it and do not seal it in any way.
- Not all materials are suitable for dry ice storage. Here are some suggestions:
- Do not use porcelain, ceramic or glass. The intense cold of dry ice causes these materials to contract until they break.
- Do not use metal containers you care about. Dry ice spoils and deforms them.
- USA sturdy plastic containers (such as portable camping refrigerators or thermal boxes).
- Uses the thermos but don't seal them.
Step 7. Alternatively you can use a can of CO2.
If you can't get a carbon dioxide fire extinguisher, you can use the same method but with a can of CO2 pressurized (available online and in hardware stores in the welding department). The procedure is virtually the same: wrap the pillowcase around the nozzle and spray the gas for a couple of seconds, collect the dry ice that accumulates in pieces on the bottom of the pillowcase. This method requires the same security measures as the previous one.
- Before purchasing the can, make sure that an extension tube is also available, which is sold separately. This type of cylinder emits liquid carbon dioxide from the bottom (and that's what you need to make dry ice). Without the tube, the canister will release the anhydride in the form of gas in the upper part and is not useful for your purpose. These pipes are indispensable for drawing gas in the liquid state, the cylinders that are equipped with them are marked with two white stripes, those that do not have them are black.
- If you plan on making dry ice often, you may want to invest in a specific tool that is nothing more than a hose with a nozzle at the end of which a lot of fabric is attached. This hose can be quickly connected and detached from the cylinder.
Method 2 of 2: Using Homemade Dry Ice
Step 1. Combine it with water to release a gas similar to fog
One of the most common applications of dry ice is the creation of artificial smoke or fog. This is a simple trick, just add it to the water: sprinkle a few drops of water over the ice to create a hiss and produce a lot of carbon dioxide. It is a very common scenic effect at dances, concerts, in the "haunted houses" of amusement parks and in all those places where you want to recreate a disturbing and mysterious atmosphere.
- As always, make sure you only perform this trick outdoors or in well-ventilated areas. Producing a lot of carbon dioxide in closed rooms forces oxygen to escape making it impossible to breathe.
- If you use a container with a small air intake, you can reproduce a geyser effect because the carbon dioxide will come out of the small hole with a powerful jet. The pressure may be enough to spin a small motor or pinwheel.
Step 2. Use dry ice to carbonate liquids
This application is also very common and allows you to make soft drinks (such as beer, colas, champagne and sparkling water) sparkling. Putting dry ice in the water triggers the release of carbon dioxide which, in part, remains trapped in the form of bubbles in the liquid. Although the procedures for the home production of beverages involve the use of CO2 in the form of gas instead of solid, dry ice also leads to the same results.
- Do not drink the soda while the ice is still in the liquid. Wait until it has melted and completely sublimated before drinking. Swallowing dry ice causes severe internal damage, and organ tissues are far more susceptible to frostbite than skin.
- Some people don't like the taste of sodas with dry ice. You can prepare a small tasting sample before venturing into large quantities.
Step 3. Use it to keep food and drinks frozen
Dry ice is much colder than regular ice and will obviously keep food at a lower temperature. The drawback of this technique is that food and liquids can become too cold; a bottle of champagne placed on a block of dry ice for a moment can shatter or partially freeze. So only use it to keep foods like ice cream, popsicles and the like cold.
- To proceed, first place the cold foods on the bottom of a thermal picnic crate and then cover them with dry ice. Put the lid on without sealing it. Cold air tends to go down, so this method is more effective for maintaining the temperature of food. If there is any empty space, fill it with crumpled newspaper sheets (to prevent the hot air from sublimate the dry ice quickly).
- Dry ice is also useful for storing normal solid ice inside the thermal box.
- To keep food frozen for 24 hours, you will need about 5-10 kg of dry ice (but it also depends on the size of the container you store it in).
Step 4. Dry ice can store bulk food
As much as it surprises you, solid carbon dioxide can keep foods such as cereals, beans, lentils and pasta fresh. To do this, put some dry ice on the bottom of the thermal crate. Make sure there is no frost on the ice, as it could be a source of moisture. Add the foods. Put the lid on without sealing it for about 5-6 hours. The ice must sublimate completely until no solid residues remain. At this point, seal the lid.
- When all the ice turned into CO2 in the gaseous state, it will have forced all the air out of the container. This is because carbon dioxide is heavier than air and has occupied its place inside the thermal box. Under these conditions, it is very difficult for bacteria or insects to survive the gas, so food lasts longer.
- For this method you need to use 125g of dry ice in a 20 liter container.
Step 5. Use it to crumple solid materials
As mentioned above, dry ice is able to deform some metals and ceramics on contact alone. In some situations, this property is very useful. Here are some examples:
-
Repair dents on the car:
if you have a small dent on the bodywork and the metal seems to be pushed inwards, dry ice can come to your aid. Put on thick gloves and press the piece of ice on the dent. If you can, also press against the inside of the body. Ice will form on the metal for 5 cm all around the dent. Finally remove the dry ice, wait for the area to warm up and repeat if necessary.
-
Remove the floor tiles:
this trick is great for peeling a tile or two off the floor. Place a piece of dry ice in the center of the tile so that it touches the entire surface. Wait until it's completely frozen. If the tile doesn't come off on its own, tap it lightly and use a screwdriver for prying.
Step 6. Use it to kill pests in the garden
Since carbon dioxide is heavier than air, it forces the latter out of a container (just like in the technique of storing bulk foods). This principle can be applied to kill moles, rodents and any other pests or animals you find in the garden. Push small pieces of dry ice (2-5 cm) into each rodent hole and close the opening with earth. Repeat this process in as many holes as you can find, in theory for all the holes the rodent dug. Ice sublimates and turns into gas, asphyxiating parasites.
Advice
- If you need dry ice in large quantities, your best bet is to go to a wholesaler. In Italy it is not easy to find it on the market, you should do some research online.
- If you have to use it often, for example for work, it is worth buying a machine that produces it. But know that it costs several thousand euros.
Warnings
- Handle dry ice in a well-ventilated room, because solid carbon dioxide turns into gas, replacing the oxygen in the air.
- When storing it, do not put a lid on the container. Dry ice sublimates and the gas must dissipate in the air. The container will explode if you leave it closed.
- Don't let dry ice touch your bare skin. You may have a painful frostbite.
- If you are a child, perform this experiment only under adult supervision and use thick leather gloves to handle dry ice.
