chemistry

Tetraamminecopper(II) sulfate

Tetraamminecopper(II) sulfate 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 Tetraamminecopper(II) sulfate rather than just read about it. In short: Tetraamminecopper(II) sulfate monohydrate, or more precisely tetraammineaquacopper(II) sulfate, is the salt with the formula [Cu(NH3)4]SO4·H2O, or more precisely [Cu(NH3)4(H2O)]SO4. This dark blue to purple solid is a sulfuric acid salt of the metal complex [Cu(NH3)4(H2O)]2+ (tetraammineaquacopper(II) cation).

Key takeaways

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

Reference excerpt

Tetraamminecopper(II) sulfate monohydrate, or more precisely tetraammineaquacopper(II) sulfate, is the salt with the formula [Cu(NH3)4]SO4·H2O, or more precisely [Cu(NH3)4(H2O)]SO4. This dark blue to purple solid is a sulfuric acid salt of the metal complex [Cu(NH3)4(H2O)]2+ (tetraammineaquacopper(II) cation). It is closely related to Schweizer's reagent, which is used for the production of cellulose fibers in the production of rayon.

Properties The deep blue crystalline solid tends to hydrolyse and evolve (release) ammonia upon standing in air. It is fairly soluble in water. The brilliant dark blue-violet color of tetraamminecopper(II) sulfate solution is due to the presence of [Cu(NH3)4]2+ (tetraamminecopper(II) cation).

Corrosion The characteristic deep blue colour of the tetraammine complex is found in brass and copper alloys where attack from ammonia has occurred, leading to cracking. The problem was first found in ammunition cartridge cases when they were stored near animal waste, which produced trace amounts of ammonia. This type of corrosion is known as season cracking.

Structure The solid state structure of tetraamminecopper(II) sulfate monohydrate confirms that the compound is a salt. The complex cation is [Cu(NH3)4(H2O)]2+ (tetraammineaquacopper(II) cation), which has a square pyramidal molecular geometry. The Cu-N and Cu-O bond length are about 210 and 233 pm, respectively, as determined by X-ray crystallography. The correct concentrations of ammonia and copper(II) sulfate solution needed to synthesize the complex can be determined by colorimetry. The combination of the correct concentrations will produce the highest absorbance read out on the colorimeter and as a result the formula of the complex can be verified.

Synthesis This compound can be prepared by adding concentrated aqueous solution of ammonia to a saturated aqueous solution of copper(II) sulfate pentahydrate followed by precipitation of the product with ethanol or isopropanol.

4 NH3 + CuSO4·5H2O → [Cu(NH3)4(H2O)]SO4 + 4 H2O

Uses The dark blue-violet color is used as a positive test to verify the presence of Cu2+ in a solution.

Gallery

References

Illustrations

Worked examples

Example 1 — a first encounter with Tetraamminecopper(II) sulfate

Start with the simplest possible case. Write down what Tetraamminecopper(II) sulfate 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 Tetraamminecopper(II) sulfate 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 Tetraamminecopper(II) sulfate 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 Tetraamminecopper(II) sulfate

In research: Tetraamminecopper(II) sulfate 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 Tetraamminecopper(II) sulfate 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: Tetraamminecopper(II) sulfate is common in secondary-school and first-year university syllabi. It links to neighbouring topics Ammine complexes, Copper complexes, Sulfates, so understanding it makes those chapters shorter.
In everyday life: Look for Tetraamminecopper(II) sulfate 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 Tetraamminecopper(II) sulfate in 20 minutes

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

Frequently asked questions

What is Tetraamminecopper(II) sulfate in simple terms?

Why does Tetraamminecopper(II) sulfate 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 Tetraamminecopper(II) sulfate?

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 Tetraamminecopper(II) sulfate.