engineering

Lithium chloride

Lithium chloride is a engineering 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 Lithium chloride rather than just read about it. In short: Lithium chloride is a chemical compound with the formula LiCl. The salt is a typical ionic compound (with certain covalent characteristics), although the small size of the Li+ ion gives rise to properties not seen for other alkali metal chlorides, such as extraordinary solubility in polar solvents (83.05 g/100 mL of water at 20 °C) and its hygroscopic properties.

Key takeaways

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

Reference excerpt

Lithium chloride is a chemical compound with the formula LiCl. The salt is a typical ionic compound (with certain covalent characteristics), although the small size of the Li+ ion gives rise to properties not seen for other alkali metal chlorides, such as extraordinary solubility in polar solvents (83.05 g/100 mL of water at 20 °C) and its hygroscopic properties.

Chemical properties

The salt forms crystalline hydrates, unlike the other alkali metal chlorides. Mono-, tri-, and pentahydrates are known. The anhydrous salt can be regenerated by heating the hydrates. LiCl also absorbs up to four equivalents of ammonia/mol. As with any other ionic chloride, solutions of lithium chloride can serve as a source of chloride ion, e.g., forming a precipitate upon treatment with silver nitrate:

LiCl + AgNO3 → AgCl + LiNO3

Preparation Lithium chloride is produced by treatment of lithium carbonate with hydrochloric acid. Anhydrous LiCl is prepared from the hydrate by heating in a stream of hydrogen chloride.

Uses

Commercial applications Lithium chloride is mainly used for the production of lithium metal by electrolysis of a LiCl/KCl melt at 450 °C (842 °F). LiCl is also used as a brazing flux for aluminium in automobile parts. It is used as a desiccant for drying air streams. In more specialized applications, lithium chloride finds some use in organic synthesis, e.g., as an additive in the Stille reaction. Also, in biochemical applications, it can be used to precipitate RNA from cellular extracts. Lithium chloride is also used as a flame colorant to produce dark red flames.

Niche uses Lithium chloride is used as a relative humidity standard in the calibration of hygrometers. At 25 °C (77 °F) a saturated solution (45.8%) of the salt will yield an equilibrium relative humidity of 11.30%. Additionally, lithium chloride can be used as a hygrometer. This deliquescent salt forms a self-solution when exposed to air. The equilibrium LiCl concentration in the resulting solution is directly related to the relative humidity of the air. The percent relative humidity at 25 °C (77 °F) can be estimated, with minimal error in the range 10–30 °C (50–86 °F), from the following first-order equation: RH=107.93-2.11C, where C is solution LiCl concentration, percent by mass. Molten LiCl is used for the preparation of carbon nanotubes, graphene and lithium niobate. Lithium chloride has been shown to have strong acaricidal properties, being effective against Varroa destructor in populations of honey bees. Lithium chloride is used as an aversive agent in lab animals to study conditioned place preference and aversion.

Precautions Lithium salts affect the central nervous system in a variety of ways. While the citrate, carbonate, and orotate salts are currently used to treat bipolar disorder, other lithium salts including the chloride were used in the past. For a short time in the 1940s lithium chloride was manufactured as a salt substitute for people with hypertension, but this was prohibited after the toxic effects of the compound (tremors, fatigue, nausea) were recognized. It was, however, noted by J. H. Talbott that many symptoms attributed to lithium chloride toxicity may have also been attributable to sodium chloride deficiency, to the diuretics often administered to patients who were given lithium chloride, or to the patients' underlying conditions.

See also Lithium chloride (data page) Solubility table

References

Handbook of Chemistry and Physics, 71st edition, CRC Press, Ann Arbor, Michigan, 1990. N. N. Greenwood, A. Earnshaw, Chemistry of the Elements, 2nd ed., Butterworth-Heinemann, Oxford, UK, 1997. R. Vatassery, titration analysis of LiCl, sat'd in Ethanol by AgNO3 to precipitate AgCl(s). EP of this titration gives %Cl by mass. H. Nechamkin, The Chemistry of the Elements, McGraw-Hill, New York, 1968.

External links Radiochemical measurements of activity coefficients, from Betts & MacKenzie, Can. J. Chem.

Illustrations

Worked examples

Example 1 — a first encounter with Lithium chloride

Start with the simplest possible case. Write down what Lithium chloride claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In engineering, 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 Lithium chloride 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 Lithium chloride 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 Lithium chloride

In research: Lithium chloride appears in engineering 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 Lithium chloride 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: Lithium chloride is common in secondary-school and first-year university syllabi. It links to neighbouring topics Alkali metal chlorides, Chlorides, Desiccants, so understanding it makes those chapters shorter.
In everyday life: Look for Lithium chloride 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.

Affiliate

Preply — study more efficiently by working with a personal tutor. 50% off.

How to study Lithium chloride in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Lithium chloride 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 Lithium chloride out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Lithium chloride in simple terms?

Why does Lithium chloride matter?

Because it connects several engineering 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 Lithium chloride?

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 Lithium chloride.