What’s the freezing point of air? [2023 Guide]

What’s the freezing point of air?

The freezing point of air is somewhere below -210°c.

How did it get it?

Simple…..

The freezing point of Nitrogen is -210°c, the main constituent of air.

Also, Oxygen, the second largest constituent, has a freezing point of -218°c.

So, the freezing point of air should be lower than -210°c but not nearer to -218°c as Oxygen is almost three times less.

Can you freeze air?

Yes, you can. Air is mainly a mixture of nitrogen gas (N2) and oxygen gas (O2). Their freezing points are -210 ºC and -219 ºC, respectively, so below -220 ºC, air would freeze. This has been achieved by using liquid helium. Helium, however, is the only known gas that does not freeze. Helium liquefies at -270 ºC.

What’s the freezing point of air?

The freezing point of air is the temperature at which water freezes, which is 0 °C, 32 °F, 273 K1. However, the air is not a pure substance but a mixture of different gases, mainly Nitrogen and Oxygen, with different freezing points.

Therefore, air does not completely freeze, but its components do when the temperature is low enough. The freezing point of Nitrogen is -210 °C, and the freezing point of Oxygen is -219 °C. So, to freeze air completely, you would need to cool it down to below -219 °C2.

What happens if you freeze air?

To answer this, let’s first look at the composition of air. We know it is a homogenous mixture of gasses like Nitrogen, Oxygen, CO2, etc. All of these gasses have vastly different freezing temperatures. Water vapour, for example, will freeze just below 0°C, while Nitrogen will only start to liquefy at -210°C.

So, it is obvious that air will solidify in layers under very extreme lab conditions only. Even gasses such as helium are hard to freeze without applying immense pressure.

Also, note that air will shrink when it cools down, creating a vacuum in case you are doing this in an insulated room. The pressure in your ‘solid’ will be intense, and this frozen state may be hard to maintain for a long time.

What is the definition of a freezing point?

“The freezing point of a substance may be defined as the temperature at which the vapour pressure of a substance in its liquid phase is equal to its vapour pressure in the solid phase”. When we talk about the vapour pressure of the solid phase, we talk about vapours formed by sublimation.

So according to this definition, all three phases, i.e., solid, liquid and gas of the substance, are present at the freezing point. (more sure about water).

If we freeze air, will a small part of it become water?

Normally, a small amount of water vapour is already in the air. So, if you freeze air, that water vapour will condense and freeze.

You are not “making” water; you are just condensing and freezing it out of the air.

Why is the melting point also the freezing point?

Because melting point and freezing point describe the same transition of matter, in this case, from liquid to solid (freezing) or, equivalently, from solid to liquid (melting).

You may not realise that while water is freezing or melting, its temperature is not changing! It is stuck at 0 ∘C during the entire melting or freezing process.

It is easier to see this for boiling points. If you heat a thermometer in water, the temperature will rise until it reaches 100 ∘C, and then it starts boiling.

And while it boils, it will stay at 100 ∘C! Until the water has all boiled away. Now, if you could trap the steam (gaseous water) and keep heating it, the steam could have a temperature higher than 100 ∘C.

However, there is enough thermal energy at the melting point to start breaking those intermolecular forces.

We observe that the temperature does not rise, but bonds are breaking, and the solid melts. Once all the solid melts, the temperature of the (now liquid) water can increase when thermal energy is added.

Can air freeze solid like water, and if so, does it expand, contract, etc.?

All gasses can hypothetically be cooled to solids, but condensation to liquids is the usual case because the temperatures required for crystallization are virtually unattainable under natural circumstances.

There are exceptions: On Mars, it gets cold enough that a fraction of the mostly carbon dioxide atmosphere freezes into dry ice at the poles during winter.

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What is the freezing point of a substance?

The freezing point of a liquid is the temperature at which it freezes, which means it becomes solid. For example, the freezing point of water is 0°C, which means water becomes ice at 0 degrees Centigrade. The freezing point of a liquid is the same as the solid’s melting point formed by the liquid’s freezing.

For example, the melting point of ice and freezing point of water is the same, which is 0° C. However, there is an energy difference between ice and water at 0°C. To convert one gram of ice at 0°C into one gram of water, you have to apply 80 calories of heat, which is called the latent heat of fusion of ice.

What is the difference between water and air when they freeze?

Freezing Water and Air

What is the difference between water and air when they freeze

Water and air have distinct properties when they freeze due to their fundamental differences in composition and behaviour.

Composition:

Water is a compound of two hydrogen atoms and one oxygen atom (H2O). When water freezes, its molecules arrange themselves into a crystalline lattice structure.

Air: Air is a mixture of gases, primarily Nitrogen (N2), Oxygen (O2), carbon dioxide (CO2), and traces of other gases. Unlike water, air does not freeze in the same way as a liquid or solid. Instead, its components condense and undergo phase changes at different temperatures.

Phase Change:

Water: When water freezes, it undergoes a phase change from a liquid to a solid state. The molecules slowly come closer together, forming a regular pattern in a hexagonal crystal lattice. This process occurs at 0 degrees Celsius (32 degrees Fahrenheit) at normal atmospheric pressure.

Air: As mentioned earlier, air does not freeze as a whole. However, its components (primarily water vapour) can condense and freeze at different temperatures, forming ice crystals. The freezing point of water vapour in air depends on various factors such as humidity, pressure, and condensation nuclei. It typically freezes below 0 degrees Celsius (32 degrees Fahrenheit).

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Visual Appearance:

Water: When water freezes, it transforms into ice, which appears solid and transparent. The crystalline structure of ice gives it a characteristic hexagonal pattern. It also expands slightly when freezing, which is why ice is less dense than liquid water, causing it to float.

Air: When water vapour in the air freezes, it forms tiny ice crystals. These crystals can take various forms, such as snowflakes or frost. Snowflakes have intricate, symmetrical patterns due to the unique arrangement of water molecules during crystallization. Frost forms as ice crystals directly on surfaces, often creating a white, feathery appearance.

In summary, water freezes to form ice, a solid crystalline structure, whereas air does not freeze as a whole, but its components, such as water vapour, can condense and freeze at different temperatures.

The freezing of water creates a transparent and hexagonal patterned solid, while frozen water vapour appears as snowflakes or frost, displaying intricate and diverse crystalline formations.

At what temperature would the air freeze?

It would happen differentially. The Nitrogen (around 78% of the atmosphere) would become solid around 63 Kelvin, and the Oxygen (most of what is left) would do the same around 54 Kelvin. All the other trace gases would behave similarly.

Why does the smoke come from the ice or any cold object, and where does it come from?

Smoke is a visible suspension of carbon or other particles in the air, typically one emitted from a burning substance. Therefore, ice cannot emit smoke. At certain times, we see a block of ice emitting some gas-like fumes – only it is not gas or vapour, but tiny droplets of water.

Water boils at 100ºC and freezes at 0ºC at sea level. At 0ºC, water is in equilibrium with ice and vapour. It is sublimating at lower temperatures (transforming from solid to vapour directly), or at higher temperatures, it evaporates. (liquid to a gas).

When ice is exposed to air, the humidity around the ice (water content of the air) condenses into tiny droplets, which we see as fumes or vapour. Condensation is the process by which a gas cools and becomes a liquid.

Water vapour is invisible.

What will happen if I place my fingers into a bowl of liquid Nitrogen?

While I was studying, I handled liquid Nitrogen on many occasions. Out of curiosity, I immersed my hand in the stuff several times.

Doing so caused the liquid Nitrogen to boil furiously, as the temperature of your skin is far higher than the -196C boiling point of the Nitrogen.

As a result, practically no liquid nitrogen remains in direct contact with the skin, and the sensation is very cold and turbulent air.

The biggest risk of injury is from touching something solid that the liquid Nitrogen has chilled.

Once, I tried to eat a small piece of peach that I’d frozen in liquid Nitrogen. It instantly froze the saliva in my mouth, adhering my tongue and inside of my cheeks to the fruit. And it stayed stuck that way until I could swallow some water. I had some blistering afterwards but no lasting injury.

What would happen if I breathed just pure Oxygen?

This minute? Nothing you would notice. You wouldn’t feel any difference. Your mental powers would not be enhanced. Your physical ability would not be improved.

For a day? You probably wouldn’t notice. But already, the Oxygen is beginning to harm your lungs subtly. Oxygen causes damage to all cells by oxidising the contents of the cell. Natural antioxidants oppose this process, but we only evolved to deal with 21% oxygen (see edit below), so these defences become overwhelmed. Lungs take the brunt because they get exposed to the greatest amount.

After 24 hours, breathing would be uncomfortable. You would have a dry cough. Your chest might feel tight.

After a few days, permanent damage starts to occur. The light, spongy lung tissue begins to scar and become firm and stiff. Even if you went back to breathing air, your lungs would not return to normal.

At pressures greater than 1 atmosphere, such as in a hyperbaric chamber, breathing 100% oxygen causes seizures after a couple of hours. So, people requiring this therapy have the atmosphere changed to a lower oxygen content every hour to reduce this risk.

Edit: Since this answer is getting a lot of views, it’s worth clarifying this point. Oxygen toxicity depends not on oxygen concentration but on partial pressure.

Partial pressure is calculated by ambient pressure multiplied by concentration. At atmospheric pressure, this works out at 21kPa. Breathing 100% oxygen at atmospheric pressure gives a partial pressure of 100kPa, which is gradually toxic. A partial pressure of 300–400kPa (in a hyperbaric chamber) leads to seizures.

But breathing pure Oxygen at one-fifth of atmospheric pressure gives a partial pressure of 20kPa, which is safe to breathe for indefinite periods. Some space vehicles have had this composition of internal atmosphere.

What happens if a person jumps into a pool of liquid Nitrogen?

First, liquid Nitrogen has a very low boiling point of -200 C. Let’s suppose a pool with such liquid is maintained at that temperature sufficiently long.

As soon as the person drops into it, they vaporise it due to heat transfer from the body. One could observe some effervescence in this system!

Nitrogen is comparatively inert at low temperatures. Hence, no chemical attack is possible.

Since such a low temperature is continuously maintained, at a point in time (in a matter of few seconds or minutes), our body will lose its energy capacity and fail to keep us warm.

Hence, the person may die of an extreme version of Hypothermia!

Is food dipped in liquid Nitrogen edible?

Liquid Nitrogen is (obviously) a liquid and is cold.

When you put food at, say, room temperature, mildly refrigerated, or even refrigerated into liquid Nitrogen, the liquid Nitrogen boils violently because the temperature difference is huge.

So, say you have some ice cream mixture. You put it in liquid Nitrogen and stir it furiously (I don’t know the procedure; I guess you stir it). The liquid Nitrogen evaporates vigorously, giving an awesome science feel to whatever you’re doing, and cools down and solidifies your mix.

So, what change has the ice cream mix undergone? Rapid cooling and maybe trapping of Nitrogen in any bubbles that might’ve formed.

These things, at least one of which is certainly aiming for, do nothing to make the food inedible.

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So, yes, food dipped in liquid Nitrogen is edible.

If you want, check out videos of cooking with liquid Nitrogen on YouTube.

Note: There is a hazard associated with cooking with liquid Nitrogen. If whatever you put into your mouth hasn’t got time to heat from the liquid nitrogen temperature, your tongue (or whatever part of your mouth touches it) will be rapidly cooled – something you don’t want to happen.