Potassium chlorate

Key takeaways

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

Reference excerpt

Potassium chlorate is the inorganic compound with the molecular formula KClO3. In its pure form, it is a white solid. After sodium chlorate, it is the second most common chlorate in industrial use. It is a strong oxidizing agent and its most important application is in safety matches.

Production

On the industrial scale, potassium chlorate is produced by the salt metathesis reaction of sodium chlorate and potassium chloride:

NaClO3 + KCl → NaCl + KClO3 The reaction is driven by the low solubility of potassium chlorate in water. The equilibrium of the reaction is shifted to the right hand side by the continuous precipitation of the product (Le Chatelier's Principle). The precursor sodium chlorate is produced industrially in very large quantities by electrolysis of sodium chloride, common table salt. The direct electrolysis of KCl in aqueous solution is also used sometimes, in which elemental chlorine formed at the anode reacts with KOH in situ. The low solubility of KClO3 in water causes the salt to conveniently isolate itself from the reaction mixture by simply precipitating out of solution. Potassium chlorate can be produced in small amounts by disproportionation in a sodium hypochlorite solution followed by metathesis reaction with potassium chloride:

3 NaOCl → 2 NaCl + NaClO3 KCl + NaClO3 → NaCl + KClO3 It can also be produced by passing chlorine gas into a hot solution of potassium hydroxide:

3 Cl2 + 6 KOH → KClO3 + 5 KCl + 3 H2O

Uses

Potassium chlorate was one key ingredient in early firearms percussion caps (primers). Another application of potassium chlorate is as the oxidizer in smoke compositions such as those used in smoke grenades.

Laboratory uses and demonstrations Potassium chlorate readily decomposes if heated while in contact with a catalyst, typically manganese(IV) dioxide (MnO2). Thus, it may be simply placed in a test tube and heated over a burner. If the test tube is equipped with a one-holed stopper and hose, warm oxygen can be drawn off. The reaction is as follows:

2 KClO3(s) + MnO2(cat) → 3 O2(g) + 2 KCl(s) Heating it in the absence of a catalyst converts it into potassium perchlorate:

4 KClO3 → 3 KClO4 + KCl With further heating, potassium perchlorate decomposes to potassium chloride and oxygen:

KClO4 → KCl + 2 O2

The safe performance of this reaction requires very pure reagents and careful temperature control. Molten potassium chlorate is an extremely powerful oxidizer and spontaneously reacts with many common materials such as sugar, as shown in the common school lab demonstration of screaming jelly babies. Explosions have resulted from liquid chlorates spattering into the latex or PVC tubes of oxygen generators and from contact between chlorates and hydrocarbon sealing greases. Impurities in potassium chlorate itself can also cause problems. Potassium chlorate reacts with sulfuric acid to form highly reactive chlorine dioxide, potassium sulfate, oxygen, and water:

4 KClO3 + 2 H2SO4 → 2 K2SO4 + 4 ClO2 (g) + O2 (g) + 2 H2O Chlorine dioxide, combined with oxygen gas (and any remaining potassium chlorate) is sufficiently reactive that it spontaneously ignites if combustible material (sugar, paper, etc.) is present.

Agriculture Potassium chlorate is used also as a pesticide. In Finland it was sold under trade name Fegabit. Potassium chlorate is used to force the blossoming stage of the longan tree, causing it to produce fruit in warmer climates.

Illicit use Militant groups in Afghanistan also use potassium chlorate extensively as a key component in the production of improvised explosive devices (IEDs). When significant effort was made to reduce the availability of ammonium nitrate fertilizer in Afghanistan, IED makers started using potassium chlorate as a cheap and effective alternative. In 2013, 60% of IEDs in Afghanistan used potassium chlorate, making it the most common ingredient used in IEDs. Potassium chlorate was also the main ingredient in the car bomb used in the 2002 Bali bombings that killed 202 people.

Safety Potassium chlorate is a very powerful oxidizer. It reacts vigorously, and in some cases spontaneously ignites or explodes, when mixed with many combustible materials. It burns vigorously in combination with virtually any combustible material, even those normally only slightly flammable (including ordinary dust and lint). Mixtures of potassium chlorate and a fuel can ignite on contact with sulfuric acid. Mixtures of potassium chlorate with lactose, sulfur, sulfides such as antimony(III) sulfide, or phosphorus are extremely shock and friction sensitive.

Illustrations

Worked examples

Example 1 — a first encounter with Potassium chlorate

Start with the simplest possible case. Write down what Potassium chlorate 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 chlorate 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 chlorate 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 chlorate

In research: Potassium chlorate 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 chlorate 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 chlorate is common in secondary-school and first-year university syllabi. It links to neighbouring topics Chlorates, Potassium compounds, Pyrotechnic oxidizers, so understanding it makes those chapters shorter.
In everyday life: Look for Potassium chlorate 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.

How to study Potassium chlorate in 20 minutes

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

Frequently asked questions

What is Potassium chlorate in simple terms?

Potassium chlorate is the inorganic compound with the molecular formula KClO3. In its pure form, it is a white solid.

Why does Potassium chlorate 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 chlorate?

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 chlorate.