chemistry

Potassium octacyanomolybdate(IV)

Potassium octacyanomolybdate(IV) 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 octacyanomolybdate(IV) rather than just read about it. In short: Potassium octacyanomolybdate(IV) is the inorganic salt with the formula K4[Mo(CN)8]. A yellow light-sensitive solid, it is the potassium salt of the cyanometalate with the coordination number eight.

Key takeaways

Potassium octacyanomolybdate(IV) 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 octacyanomolybdate(IV) to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Potassium octacyanomolybdate(IV) from memory before moving on to harder problems.

Reference excerpt

Potassium octacyanomolybdate(IV) is the inorganic salt with the formula K4[Mo(CN)8]. A yellow light-sensitive solid, it is the potassium salt of the cyanometalate with the coordination number eight. The complex anion consists of a Mo(IV) center bound to eight cyanide ligands resulting in an overall charge of −4, which is balanced with four potassium cations. The salt is often prepared as its dihydrate K4[Mo(CN)8].(H2O)2.

Preparation The dihydrate K4[Mo(CN)8] · 2 H2O can be prepared by the reduction of molybdate (MoO42-) with potassium borohydride (KBH4) in a solution with potassium cyanide and acetic acid. Yields of 70% are typical and the method is suited for scale-up.

4 MoO42- + 32 CN− + BH4− + 25 H+ → 4 [Mo(CN)8]4- + 13 H2O + H3BO3 An alternative route starts from MoCl4(Et2O)2 avoiding the need for reductants. The yield of this route is typically around 70%. This synthesis is convenient for lower batch sizes than the earlier method but the MoCl4(Et2O)2 is typically less available than the molybdate.

MoCl4(Et2O)2 + 8 KCN → K4[Mo(CN)8] + 4 KCl + 2 Et2O

Reactions Octacyanomolybdate(IV) can be oxidized to the paramagnetic octacyanomolybdate(V). The cyanide ligands in [Mo(CN)8]4- remain basic. Strong acids lead to the hydrogen isocyanide complex [Mo(CNH)8]4+, in common with many cyanometalate complexes. These ligands can be substituted by others, for example H2O. The cyanide ligands also bind to other metals, leading to cages.

References

Illustrations

Worked examples

Example 1 — a first encounter with Potassium octacyanomolybdate(IV)

Start with the simplest possible case. Write down what Potassium octacyanomolybdate(IV) 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 octacyanomolybdate(IV) 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 octacyanomolybdate(IV) 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 octacyanomolybdate(IV)

In research: Potassium octacyanomolybdate(IV) 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 octacyanomolybdate(IV) 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 octacyanomolybdate(IV) is common in secondary-school and first-year university syllabi. It links to neighbouring topics Coordination complexes, Cyano complexes, Cyanometallates, so understanding it makes those chapters shorter.
In everyday life: Look for Potassium octacyanomolybdate(IV) 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 octacyanomolybdate(IV) in 20 minutes

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Frequently asked questions

What is Potassium octacyanomolybdate(IV) in simple terms?

Potassium octacyanomolybdate(IV) is the inorganic salt with the formula K4[Mo(CN)8]. A yellow light-sensitive solid, it is the potassium salt of the cyanometalate with the coordination number eight.

Why does Potassium octacyanomolybdate(IV) 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 octacyanomolybdate(IV)?

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 octacyanomolybdate(IV).