What happens when pentahydrate copper sulphate is heated

You may need to know what happens when pentahydrate copper sulphate is heated and what can be expected. This salt is heated to make pentahydrate copper sulphide, which results in the production of hydrogen gas and elemental sulfur. Pentahydrate copper sulfate is considered a paradoxical compound because it only appears when it's heated and then turns into two different compounds (pentahydrate copper sulfide and elemental sulfur). Copper sulfate often used in bleaches, laundry treatments, or textile dyes.

What are the uses of pentahydrate copper sulphate

1. Corrosion inhibitor

This compound is used to prevent corrosion of iron, steel, aluminum, zinc, and other metals because it has natural anti-corrosion properties. It also can be used to control rust on aluminum and zinc. Why? When pentahydrate copper sulfate is introduced into a low pH environment (to make pentahydrate copper sulphide), its crystal structure collapses causing the formation of hydrogen gas. Hydrogen gas is highly reactive to other elements and has strong bonding abilities with iron or iron oxide, which usually occurs when metal corrodes in acidic environments. You can imagine that if you apply pentahydrate copper sulfide to metal, it will be corroded very soon before long.

2. Antifouling

Antifouling is a coating used to prevent marine organisms on the hull and pipelay of ships from adhering to the surface. Antifouling agents are applied to prevent fouling or biofouling. A common antifoulant is 1% pentahydrate copper sulfate. This compound also can be used as a nutrient for other kinds of algae that occur in marine environments and affect ships.

3. Food additive

It's not very tasty, but this compound is added to food for its preservation, flavor, or coloration effect. Its anti-microbial properties also can be used to prevent food from contamination and growth of harmful microorganisms. It can also be used to replace some components of food, such as sodium chloride (salt). 1% sodium chloride can substitute with 1 g pentahydrate copper sulfate.

4. Pigment

This compound is used as a pigment in water color and in toothpaste, mouthwash, deodorant, and other products.

5. Water treatment

It can be used to clear water by reducing the concentration of dissolved substances, including sulfate and micronutrients, such as copper and manganese.

6. Medicine

This compound can be used in many kinds of medicine, such as those used in human, cattle and poultry. Because of its strong antifouling ability, it's also used as a preservative or chemical inhibitor. It can also be used to kill harmful microorganisms (bacterium and yeast) or fungus.

7. Activator

Pentahydrate copper sulfate can also be used as a catalyst in chemical reactions such as organic synthesis and electrolysis; this compound is especially useful for organic synthesis because of its good catalytic activity. The copper sulfate is generally produced by electrolysis of the solution containing 0.2 mole/L of copper sulfate, and the catalyst is filtered and dried.

8. Insecticide and rodenticide

This compound is used in pesticides because of its strong antifouling, fumigant and pesticide properties. This compound also can be used as a cultural control agent, to kill insects and gophers.

9. Pigment in paper pulp manufacturing

Its color (greenish blue, metallic luster) is widely used in the manufacture of paper pulp, especially for the production of high quality printing paper (eg security paper). This compound also can be added to the white paint to give it a greenish color. After white paint dried up and exposed to air, it turns into yellowish green. This explains what happens when pentahydrate copper sulphate is heated.

10. Ink

It can be used in the production of ink to replace potassium ferricyanide. Nowadays, pentahydrate copper sulfate is used to make green ink and pigment for colored inks. But its antimicrobial properties also have been widely used in the production of anti-counterfeiting stamps.

11. Toothpaste, mouthwash and deodorant

This compound contains anti-fungal properties and acts as an anti-microbial agent can be effective against bacteria, fungi, and some viruses that cause oral disease such as gingivitis or bad breath (halitosis).

12. Decorative paper

This compound is used as a printing ink in decorative papers, especially for the production of color printing papers and varnishes for water-based or dye-based paint. It can also be used as an ultraviolet absorber or light diffuser in sunscreens.

13. Disinfectant, bleaching agent and detergent

It can be used to kill bacteria, yeasts, mold and fungus in water, air (dust), sewage water, food, pharmaceuticals etc. It also can be used as a detergent to clean different kinds of household objects such as glassware and utensils.

In conclusion, when pentahydrate copper sulphate is heated and make pentahydrate copper sulphide, it becomes a great corrosion inhibitor that causes the formation of hydrogen gas. This gas is naturally reactive with other elements and has strong bonding effects on iron oxide or zinc oxide. That's why this gas is widely used in the production of anti-corrosion coatings for metal surfaces.