Dry ice is often used to make spooky fog drinks at Halloween time or sometimes it is used for a cool effect in cocktails or to make smoke effects in a pool or on a stage. But how long does dry ice last in water and what can you do to make it last longer?
How long dry ice lasts in water depends on the size of the dry ice as well as the total volume and temperature of the water.
A small pellet of dry ice might last 15-30 minutes in a drink or small container, while a large 50-100 pound block of dry ice in a swimming pool can last hours. Dry ice fog will only last 10-15 minutes because the water will become too cold for fog to continue forming.
It’s important to note that ice melts faster in water than in air. This is not because of any fancy chemical reaction but rather that water has more heat capacity than air and can also conduct heat better than air.
How Long Does Dry Ice Last In Water?
A lot of websites will say that dry ice only lasts 10-15 minutes in water but this is completely untrue. They think this because dry ice will stop making fog at around 10-15 minutes because the water will get too cold for this to work anymore.
However, even when this happens the dry ice is often still there.
How long dry ice lasts in water depends on:
- The size of the dry ice
- The volume of the water
- The temperature of the water
A small piece of dry ice dropped in a hot tub won’t last very long. But a giant piece of dry ice put in a small bowl of already cold water will simply freeze the water and then go on to last hours.
Why Does Dry Ice Sublimate Faster In Water Than In Air?
Dry ice sublimates (turns from a solid into a gas) much faster in water than it does when it is just left out in the air. Why does this happen and why does dry ice disappear faster in water?
The reason for this is water is denser than air and thus has more heat capacity. This means it can deliver more heat energy to the dry ice block quicker, thus making it melt faster.
Water is also a better conductor of heat than air and this also helps it to deliver more heat energy to the dry ice faster than air, again making the dry ice disappear faster.
More heat = more sublimation = dry ice disappearing faster
It’s the same with regular water ice. Regular water ice will melt faster in water than in does in air for this exact same reason.
Dry ice doesn’t melt faster in water because of any fancy chemical reaction between the frozen carbon dioxide and the water. It’s simply the water contains more heat energy and thus makes the dry ice melt faster.
How To Make Dry Ice Last Longer In Water
It’s actually quite difficult to make dry ice last longer in water, because either the dry ice will completely freeze the water or the water will completely melt the dry ice. That depends on how much dry ice and how much water there is.
Are you actually trying to make the dry ice last longer in the water or do you just want the dry ice fog effect to last longer?
If you’re just looking to make the dry ice fog effect last longer then click here to learn how to do that.
Below is how to actually make the dry ice last longer in water without completely disappearing:
Use More and Larger Dry Ice
The more dry ice you use, and the large individual blocks of dry ice you use, will make the dry ice last longer in the water.
Larger blocks have less surface area than lots of little blocks and therefore they sublimate slower.
Lots of dry ice will help to cool down the water faster and that will slow the melting of the dry ice.
Just like regular ice hot water will melt dry ice faster than cold water will. So putting your dry ice in already cold water will make it last longer.
However, what is likely to happen here is that your dry ice will become covered in frozen water and then float to the surface. Eventually it will freeze all the water and turn it into ice.
Why Does Dry Ice Make Fog/Smoke When Placed in Water?
Dry ice makes water look like it’s boiling and it makes a cool fog or smoke effect that flows over your cup (or cauldron) and then settles on the floor.
But what is exactly happening here and why does the freezing cold dry ice make that fog effect when placed in water?
The reason it does this is because the cold dry ice gas condenses the water vapor above the water into tiny droplets which is what makes the fog.
Dry ice sublimates at room temperature. This means it turns directly from a solid into a gas. You can think of it as the dry ice is boiling, even at room temperature.
When you throw dry ice into warm water it speeds up this sublimation process so more gas is released faster.
This gas rises to the surface of the water.
The dry ice gas is cold. As it rises to the surface of the water it mixes with the water vapour in the air above the water.
The dry ice gas cools down the water vapor gas above the warm water and makes it condense into tiny water droplets which we see as fog.
Once the fog escapes your container it is colder than the surrounding air so it falls to the ground until it disappears.
How To Make Dry Ice Fog Last Longer
Dry ice fog usually lasts for around 10-15 minutes depending on the size of the dry ice and the volume of the water.
Dry ice fog works when the water is warm enough to make enough water vapor to cause the fog.
Over time the dry ice cools the water down and once the water is too cold it will not longer produce fog and eventually water will freeze around the dry ice and make it float to the surface.
If you want to make dry ice fog last longer you need to achieve two things:
Have enough dry ice that is doesn’t completely disappear quickly
Have enough hot water that the fog effect continues and the water does freeze
Here are some ways to make dry ice fog last longer:
- Put a heating element under your water container to keep the water hot enough that the fog effect continues
- Uses a large but shallow bowl/container so there is lots of warm water around the dry ice. This will ensure the water doesn’t slow down as quickly
- Continually replenish your container by tipping out the cold water and adding more hot water to the dry ice
Can You Put Water On Dry Ice?
Yes you can put water on dry ice.
If you tip water on dry ice the heat from the water will make the dry ice sublimate (turn from a solid into a gas) faster.
This release of gas will simply push the water off the dry ice.
You make get some frozen droplets of water stuck to the dry ice or surrounding the dry ice.
Colder water is more likely to freeze when it touches the dry ice compared to hot water which is more likely to be pushed off the dry ice.
How Long Does Dry Ice Last In a Pool?
Dry ice does not last very long in a pool. The length of time depends on the size of the dry ice and the heat of the pool. A small piece of dry ice will only last a couple of minutes in a pool whereas a large 50-100 pound block can last up to an hour in a pool.
Water contains more heat capacity than air and because there is so much water in a pool the dry ice doesn’t cool the water down much.
The pool water will cause the dry ice to disappear much faster compared to it just being left in the open air.
Can You Drink Water After Dry Ice Has Been In It?
When dry ice is placed in water it releases carbon dioxide gas. This is the same gas that makes your soda fizzy so it is perfectly safe to be consumed.
You do need to make sure that the dry ice you are using is food grade dry ice. If it isn’t food grade then it isn’t considered safe for humans to consume.
Can You Touch Dry Ice In Water?
You should never touch dry ice with your bare skin as it can cause frostbite in a matter of seconds.
Even when dry ice is in water it is still extremely cold. Dry ice has a temperature of -109.3°F (-78.5°C) and this doesn’t change when it’s in water. So no you should NOT touch dry ice when it’s in water unless you have waterproof protective gloves on.
Trying to pick up dry ice with fabric gloves whilst the dry ice is in water can also be dangerous. The fabric gloves will get wet with water. This water conducts heat and so the cold from the dry ice can reach your skin much faster and again cause frostbite.
The only time you can really touch dry ice in water is when the dry ice has caused regular water ice to form a layer around it. This will usually cause the dry ice to float to the surface.
However, this is still extremely cold and you should avoid touching it where possible.
Is Dry Ice Safe In Cocktails?
Dry ice can be a great way to make a cool fog effect in cocktails. Dry ice is safe to add to cocktails as long as the dry ice is food grade.
If the dry ice is not food grade then it should not be added to cocktails and this is not deemed safe for human consumption.
When dry ice is placed in a cocktail it will sublimate (turn from a solid into a gas) and it will cool down the cocktail in the process. Dry ice releases carbon dioxide gas and in the small quantities it is used in in cocktails it is not dangerous. It’s actually the same gas that is used in soda, so it may give your cocktail a fizzy taste.
Under no circumstance should dry ice be consumed as dry ice can kill you. Do not swallow the dry ice as it can cause internal damage and you’ll need to go to hospital.