chemistry

Halazone

Halazone 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 Halazone rather than just read about it. In short: Halazone (4-(dichlorosulfamoyl)benzoic acid) is a chemical compound whose formula can be written as either C7H5Cl2NO4S or (HOOC)(C6H4)(SO2)(NCl2). It has been widely used to disinfect drinking water.

Key takeaways

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

Reference excerpt

Halazone (4-(dichlorosulfamoyl)benzoic acid) is a chemical compound whose formula can be written as either C7H5Cl2NO4S or (HOOC)(C6H4)(SO2)(NCl2). It has been widely used to disinfect drinking water.

Uses Halazone tablets have been used to disinfect water for drinking, especially where treated tap water is not available. A typical dosage is 4 mg/L. Halazone tablets were commonly used during World War II by U.S. soldiers for portable water purification, even being included in accessory packs for C-rations until 1945. Halazone was widely used by Marine infantry units during the Vietnam War. Halazone has largely been replaced in that use by sodium dichloroisocyanurate. The primary limitation of halazone tablets was the very short usable life of opened bottles, typically three days or less, unlike iodine-based tablets which have a usable open bottle life of three months. Dilute halazone solutions (4 to 8 ppm of available chlorine) has also been used to disinfect contact lenses, and as a spermicide.

Mechanism of action Halazone's disinfecting activity is mainly due to the hypochlorous acid (HClO) released by hydrolysis of the chlorine-nitrogen bonds when the product is dissolved in water:

(R1)(R2)NCl + H2O → HOCl + (R1)(R2)NH The hypochlorous acid is a powerful oxidizer and chlorinating agent that destroys or denatures many organic compounds.

Production Halazone can be prepared by chlorination of p-sulfonamidobenzoic acid. Another synthesis route is the oxidation of dichloramine-T with potassium permanganate in a mild alkaline medium.

See also Bleach Chlorine-releasing compound Chloramine-T (tosylchloramide sodium salt), another water disinfection agent. Water chlorination Monalazone

References

Illustrations

Worked examples

Example 1 — a first encounter with Halazone

Start with the simplest possible case. Write down what Halazone 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 Halazone 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 Halazone 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 Halazone

In research: Halazone 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 Halazone 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: Halazone is common in secondary-school and first-year university syllabi. It links to neighbouring topics Antiseptics and disinfectants, Benzoic acids, Nitrogen–halogen compounds, so understanding it makes those chapters shorter.
In everyday life: Look for Halazone 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 Halazone in 20 minutes

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

Frequently asked questions

What is Halazone in simple terms?

Halazone (4-(dichlorosulfamoyl)benzoic acid) is a chemical compound whose formula can be written as either C7H5Cl2NO4S or (HOOC)(C6H4)(SO2)(NCl2). It has been widely used to disinfect drinking water.

Why does Halazone 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 Halazone?

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 Halazone.