chemistry

Potassium dicyanoaurate

Potassium dicyanoaurate is a chemistry 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 Potassium dicyanoaurate rather than just read about it. In short: Potassium dicyanoaurate (or potassium gold cyanide) is an inorganic compound with formula K[Au(CN)2]. It is a colorless to white solid that is soluble in water and slightly soluble in alcohol.

Key takeaways

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

Reference excerpt

Potassium dicyanoaurate (or potassium gold cyanide) is an inorganic compound with formula K[Au(CN)2]. It is a colorless to white solid that is soluble in water and slightly soluble in alcohol. The salt itself is often not isolated, but solutions of the dicyanoaurate ion ([Au(CN)2]−) are generated on a large scale in the extraction of gold from its ores.

Production In mining of gold from dilute sources, gold is selectively extracted by dissolution in aqueous solutions of cyanide, provided by dissolving sodium cyanide, potassium cyanide and/or calcium cyanide. The reaction for the dissolution of gold, the "Elsner Equation", is:

4 Au + 8 KCN + O2 + 2 H2O → 4 K[Au(CN)2] + 4 KOH In this process, oxygen is the oxidant. It can also be produced by reaction of gold(I) salts with excess potassium cyanide.

AuCl + 2 KCN → K[Au(CN)2] + KCl

Structure

Potassium dicyanoaurate is a salt. The dicyanoaurate anion is linear according to X-ray crystallography. On the basis of infrared spectroscopy, the dicyanoaurate anion adopts a very similar structure in sodium dicyanoaurate (NaAu(CN)2).

Uses Dicyanoaurate is the soluble species that is the focus of gold cyanidation, the hydrometallurgical process for winning gold from dilute ores. In fact, sodium cyanide, not the potassium salt, is more widely used in commercial processes. Aside from its major use as an intermediate in the extraction of gold, potassium dicyanoaurate is often used in gold plating applications.

Related compounds The compound containing gold(III) cyanide is also known: potassium tetracyanoaurate(III), K[Au(CN)4]. Its use is less common. The potassium ion can be replaced with quaternary ammonium cations as in tetrabutylammonium dicyanoaurate.

Safety The ingestion of gram quantities of potassium dicyanoaurate can lead to death due to gold that inhibits enzyme rhodanese, which the body uses to detoxify cyanide.

References

Illustrations

Worked examples

Example 1 — a first encounter with Potassium dicyanoaurate

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

In research: Potassium dicyanoaurate appears in chemistry 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 Potassium dicyanoaurate 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: Potassium dicyanoaurate is common in secondary-school and first-year university syllabi. It links to neighbouring topics Aurates, Cyanides, Cyanometallates, so understanding it makes those chapters shorter.
In everyday life: Look for Potassium dicyanoaurate 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 Potassium dicyanoaurate in 20 minutes

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

Frequently asked questions

What is Potassium dicyanoaurate in simple terms?

Potassium dicyanoaurate (or potassium gold cyanide) is an inorganic compound with formula K[Au(CN)2]. It is a colorless to white solid that is soluble in water and slightly soluble in alcohol.

Why does Potassium dicyanoaurate matter?

Because it connects several chemistry 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 Potassium dicyanoaurate?

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 Potassium dicyanoaurate.