science

Liquefied gas

Liquefied gas is a science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Liquefied gas rather than just read about it. In short: Liquefied gas (sometimes referred to as liquid gas) is a gas that has been turned into a liquid by cooling or compressing it. Examples of liquefied gases include liquid air, liquefied natural gas, and liquefied petroleum gas.

Key takeaways

Liquefied gas belongs to science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Liquefied gas to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Liquefied gas from memory before moving on to harder problems.

Reference excerpt

Liquefied gas (sometimes referred to as liquid gas) is a gas that has been turned into a liquid by cooling or compressing it. Examples of liquefied gases include liquid air, liquefied natural gas, and liquefied petroleum gas.

Liquid air

At the Lister Institute of Preventive Medicine, liquid air was introduced as an agent in biological research. An inquiry into the intracellular constituents of the typhoid bacillus, initiated under the direction of Doctor Allan Macfadyen, necessitated the separation of the cell-plasma of the organism. The method initially adopted for the disintegration of the bacteria was to mix them with silver-sand and churn the whole up in a closed vessel in which a series of horizontal vanes revolved at high speed. But certain disadvantages are attached to this procedure, and accordingly, some means were sought to do away with the sand and triturate the bacilli per se. This was found in liquid air, which, as had long before been shown at the Royal Institution, has the power of reducing materials like grass or plant leaves to such a state of brittleness that they can easily be powdered in a mortar. By its aid, a complete trituration of the typhoid bacilli was accomplished at the Jenner Institute, and the same process, already applied with success also to yeast cells and animal cells, was extended in other directions. When air is liquefied, oxygen and nitrogen condense simultaneously. However, owing to its greater volatility, the latter boils off more quickly of the two, so that the remaining liquid becomes progressively richer in oxygen.

Liquefied natural gas

Liquefied natural gas is natural gas that has been liquefied for storage or transport. Since transporting natural gas requires a large network of pipelines that crosses various terrains and oceans, significant investment and long-term planning are required. Before transport, natural gas is liquefied by pressurization. The liquefied gas is then transported through tankers with special airtight compartments. When the tanks are opened, and the liquid is exposed to atmospheric pressure, it boils off due to latent heat from the air or the container.

See also Liquid oxygen Liquid nitrogen Liquid hydrogen Liquid helium

References

This article incorporates text from a publication now in the public domain: Dewar, James (1911). "Liquid Gases". In Chisholm, Hugh (ed.). Encyclopædia Britannica. Vol. 16 (11th ed.). Cambridge University Press. pp. 744–759.

Illustrations

Worked examples

Example 1 — a first encounter with Liquefied gas

Start with the simplest possible case. Write down what Liquefied gas claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Liquefied gas before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Liquefied gas ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Liquefied gas

In research: Liquefied gas appears in science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Liquefied gas in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Liquefied gas is common in secondary-school and first-year university syllabi. It links to neighbouring topics Cryogenics, Laboratory techniques, so understanding it makes those chapters shorter.
In everyday life: Look for Liquefied gas outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Liquefied gas in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Liquefied gas means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Liquefied gas out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Liquefied gas in simple terms?

Why does Liquefied gas matter?

Because it connects several science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Liquefied gas?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Liquefied gas.