Copper(II) sulfate Facts for Kids

Copper(II) sulfate


General
Systematic name	copper(II) sulfate
Other names	cupric sulfate, copper sulfate, chalcanthite, blue vitriol, bluestone
Molecular formula	CuSO₄
Molar mass	143.61 g/mol
Appearance	blue solid crystals when hydrated, white solid when anhydrous
CAS number	7758-98-7
Properties
Density and phase	3.603 g/cm³ (anhydrous), 2.284 g/cm³ (hydrated)
Solubility in water	31.6 g/100 ml (0°C)
Solubility in ethanol	insoluble, both forms
Solubility in methanol	hydrate is soluble
Melting point	150°C (423 K) dehydrates, 650°C decomp.
Structure
Coordination geometry	octahedral
Crystal structure	triclinic
Hazards
MSDS	MSDS
Main hazards	(Xn) Harmful (Xi) Irritant (N) Dangerous for the environment
NFPA 704	0 2 1
R/S statement	R: R22, R36/38, R50/53 S: S2, S22, S60, S61
Related compounds
Other anions	Copper(II) chloride, Copper(II) oxide
Other cations	Sodium sulfate, Manganese sulfate, Iron(II) sulfate
Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) Disclaimer

Copper(II) sulfate, also known as cupric sulfate or bluestone, is a common chemical compound. Its chemical formula is CuSO₄. It contains copper and sulfate ions. This compound is usually a blue solid. It can be used to kill fungi and to make copper metal purer. You might see it in chemistry sets and during science lessons at school.

What is Copper(II) Sulfate?
- Physical Features
- How it Reacts
Where is it Found?
How is it Made?
What is it Used For?
Safety Information
Related pages
Images for kids
See also

What is Copper(II) Sulfate?

Physical Features

Copper(II) sulfate looks blue when it has water molecules attached to it. We call this "hydrated." When it doesn't have water, it's a whitish solid, and we call it "anhydrous."

Usually, the blue form has five water molecules connected to each copper sulfate molecule. You can remove this water by heating it up. If you add water back, it turns blue again. It can even absorb water from the air and become hydrated.

How it Reacts

Copper(II) sulfate is a weak oxidizing agent. This means it can take electrons from other substances.

It reacts with most metals to form copper and a metal sulfate. For example, if you put iron in copper sulfate solution, you get copper metal and iron(II) sulfate:

Fe + CuSO₄ → FeSO₄ + Cu

It also reacts with substances like sodium hydroxide or potassium hydroxide. This reaction creates copper(II) hydroxide:

CuSO₄ + 2 NaOH → Cu(OH)₂ + Na₂SO₄

When it reacts with sodium carbonate, it forms copper(II) carbonate:

CuSO₄ + Na₂CO₃ → CuCO₃ + Na₂SO₄

If you mix it with ammonia, it makes a dark blue solution. This solution is so strong it can even dissolve cotton fibers.

CuSO₄ + 4 NH₃ → Cu(NH₃)₄SO₄

When heated to very high temperatures, copper(II) sulfate breaks down. It turns into copper(II) oxide and sulfur trioxide:

CuSO₄ → CuO + SO₃

Like all copper compounds, it creates a blue-green color when heated in a flame. This is called a flame test.

A flame test showing the blue-green color of copper.

Where is it Found?

Copper(II) sulfate can be found naturally as a mineral called chalcanthite. This mineral is easily dissolved by water, so it's mostly found in dry places.

Chalcanthite is usually blue or green. When it's exposed to air, its bright blue color can fade. Some mineral collectors like to find it.

How is it Made?

Making copper sulfate using electrolysis with copper and sulfuric acid.

Making copper sulfate in a small lab isn't common because it's easier to buy it. However, there are ways to make it:

You can make it using electrolysis. This involves passing electricity through a solution of sulfuric acid with copper electrodes. This process also produces hydrogen gas.

Cu + H₂SO₄ → CuSO₄ + H₂

It can also be made by reacting copper(II) oxide, copper(II) hydroxide, or copper(II) carbonate with sulfuric acid:

CuO + H₂SO₄ → H₂O + CuSO₄

Cu(OH)₂ + H₂SO₄ → 2 H₂O + CuSO₄

CuCO₃ + H₂SO₄ → H₂O + CuSO₄ + CO₂

Another way is to add copper to hot, concentrated sulfuric acid:

Cu + 2H₂SO₄ → CuSO₄ + H₂O + SO₂

You can also make it by reacting copper with a mix of nitric acid and sulfuric acid.

What is it Used For?

Copper(II) sulfate is a very useful copper compound with many different applications:

Killing Pests: It can be used to kill algae and fungi. Sometimes, fungi can become resistant to it, meaning it no longer works. It can also be mixed with lime to create a similar fungus killer.
Fish Health: It's used to treat aquarium fish for certain infections.
Detecting Sugars: In chemistry, it helps detect certain sugars. When a sugar reduces it, copper(II) sulfate changes into red copper(I) oxide.
Chemistry Experiments: It's often found in chemistry sets. It's great for showing a reaction called a "displacement reaction." In this reaction, one metal replaces the copper in copper sulfate, creating new copper metal and a different metal sulfate.
Hydrated vs. Anhydrous: It's also used to show the difference between "hydrated" (with water) and "anhydrous" (without water) chemicals.
Purifying Copper: Copper(II) sulfate is used to make copper metal purer. Here's how it works:
- A thin piece of pure copper and a thicker, impure piece of copper are placed in a copper sulfate solution.
- The thin, pure copper is connected to the negative side of a power source (the cathode).
- The thick, impure copper is connected to the positive side (the anode).
- When electricity flows, the copper from the impure piece dissolves into the solution. Then, pure copper from the solution sticks onto the thin, pure copper piece. Any unwanted substances (impurities) from the thick piece fall to the bottom.

Safety Information

Copper sulfate can be harmful to humans if not handled carefully. It is very harmful to fish.

Skin and Eyes: It can irritate your skin and eyes. Always wash your hands after touching it and avoid getting it in your eyes.
If Swallowed: If someone accidentally swallows it, it can cause nausea (feeling sick to your stomach). It often makes a person throw up naturally. However, if too much is swallowed and stays in the stomach, it can cause serious health problems. It is important to never taste or eat copper sulfate.