Is Oxygen Solid, Liquid or Gas? (+ 3 More Things to Know)

Oxygen is a gas at room temperature and pressure. ¹ However, if the temperature is lowered below -218.4 °C, oxygen will solidify into a light-blue crystalline solid. If the temperature is increased above -183.0 °C and the pressure is higher than 1 atm, oxygen will exist as a pale-blue liquid. ^{2 3}

Well, this was just a simple answer. But there are few more things to know about this topic which will make your concept super clear.

So let’s dive right into it.

Why does oxygen exist as a gas at room temperature?

Oxygen exists as a gas at room temperature because of its molecular structure and the intermolecular forces that hold its molecules together. Oxygen gas (O2) is composed of two oxygen atoms covalently bonded together to form a diatomic molecule.

At room temperature and standard atmospheric pressure, the intermolecular forces between oxygen molecules are relatively weak, allowing them to move around and spread out to fill any available space, giving oxygen its gaseous state.

The relatively low boiling point of oxygen (-183 °C or -297 °F) also contributes to its gas state at room temperature. ⁴

It’s worth noting that the behavior of oxygen is due to a combination of factors, including its molecular structure, intermolecular forces, and external conditions like temperature and pressure.

These factors can influence the state in which a substance exists, whether it’s a gas, liquid, or solid.

Does oxygen exist in liquid or solid state?

Yes, oxygen can exist in both liquid and solid states under certain conditions.

At temperatures below -183 °C (-297 °F) and under high pressure, oxygen can exist in a liquid state. Liquid oxygen is pale blue and has a density of about 1.14 g/mL. ⁵ It is commonly used as an oxidizer in rockets and as a coolant for some industrial processes. ^{6 7}

At even lower temperatures, below -218.4 °C (-361.1 °F) and at standard atmospheric pressure, oxygen can exist as a pale blue solid. This is known as solid oxygen or molecular oxygen (O2). Solid oxygen is a highly reactive material and can be dangerous to handle, as it can ignite spontaneously under certain conditions.

It’s worth noting that the conditions required to convert oxygen to a liquid or solid state are not easily achieved under normal circumstances, and as a result, oxygen is typically encountered in its gaseous state.

How is gaseous oxygen different from solid oxygen and liquid oxygen?

Gaseous oxygen, solid oxygen, and liquid oxygen differ in their physical properties, such as their molecular structure, density, and reactivity.

Gaseous oxygen

Gaseous oxygen (O2) is a diatomic gas composed of two oxygen atoms that are weakly attracted to each other by intermolecular forces. ^{8 9}

It has no definite shape or volume, and can easily expand to fill any container.

It is relatively unreactive at normal temperatures and pressures, but can support combustion, making it essential for many combustion-based processes.

Solid oxygen

Solid oxygen is a crystalline form of oxygen in which oxygen molecules (O2) are arranged in a lattice structure.

It is a pale blue solid that is highly reactive and can be explosive when exposed to heat, friction, or shock. Solid oxygen has a much higher density than gaseous oxygen, and its molecules are tightly packed together.

Liquid oxygen

Liquid oxygen is a pale blue liquid that is composed of oxygen molecules (O2) that are loosely held together by intermolecular forces.

It has a density of about 1.14 g/mL and can be extremely cold, with a boiling point of -183 °C (-297 °F) at standard atmospheric pressure. Liquid oxygen is used as an oxidizer in rockets and as a coolant in industrial processes. ¹⁰

In summary, gaseous oxygen is a diatomic gas that is relatively unreactive at normal temperatures and pressures, solid oxygen is a highly reactive crystalline form of oxygen, and liquid oxygen is a dense and extremely cold liquid that is used as an oxidizer and coolant.

Further reading

Is Lithium Solid, Liquid or Gas?
Is Magnesium a Solid, Liquid or Gas?
Is Nitrogen a Solid, Liquid or Gas?
Is Neon a Solid, Liquid or Gas?
Is Carbon a Metal, Nonmetal or Metalloid? 

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