05

2019

06

The reaction between water and anhydrous copper sulfate

Anhydrous copper sulfate is a white solid, which reacts with water to form copper sulfate pentahydrate, which is blue. There will be blue precipitation, because anhydrous copper sulfate will combine with water to form copper sulfate, which reduces the mass of solvent in the saturated solution, so more precipitation will occur, but it will not be absorbed dry. Formula: CuS04+5H20=CuS04•5H20.


Anhydrous copper sulfate is a white solid, which reacts with water to form copper sulfate pentahydrate, which is blue. There will be blue precipitation, because anhydrous copper sulfate will combine with water to form copper sulfate, which reduces the mass of solvent in the saturated solution, so more precipitation will occur, but it will not be absorbed dry. Formula: CuS04+5H20=CuS04•5H20.

1. Uses

Anhydrous copper sulfate (white powder after heating and dehydration of copper sulfate), chemical formula Cus04, turns blue when it comes into contact with water, and is usually used in experiments to prove the presence of water. Anhydrous copper sulfate is an important raw material for the preparation of other copper salts in the chemical industry. It is mainly used in raw materials for antifouling paint on the bottom of ships, desiccants, catalysts, etc.

Anhydrous copper sulfate is also used to prepare Bordeaux mixture (a pesticide that mainly kills insects by the toxicity of copper ions). It mainly uses the Cu(0H)2 precipitate generated in CuS04+Ca(0H)2(a small amount)=Cu(0H)2↓+Cas04 to form a suspension, which makes it easier for the pesticide to be adsorbed on the leaves to achieve the purpose of lasting efficacy.

2. Preparation

The copper sulfate solution is concentrated and crystallized to obtain a blue copper sulfate pentahydrate with a relative density of 2.284. Anhydrous copper sulfate is very stable at room temperature and pressure, does not deliquesce, and will gradually weather in dry air. When heated to 45°C, it loses two molecules of crystal water, loses four molecules of crystal water at 110°C, and loses all crystal water at 150°C to become anhydrous. Anhydrous substances are also easy to absorb water and turn into blue copper sulfate pentahydrate. This property is often used to test whether certain liquid organic matter contains trace amounts of water. Heating anhydrous copper sulfate to 650℃ can decompose it into black copper oxide, sulfur dioxide and oxygen.

Copper sulfate is a natural hydrous copper sulfate, a widely distributed sulfate mineral. It is a secondary mineral formed when copper sulfide is decomposed by oxygen. Copper sulfate is produced in the oxidation zone of copper deposits and often appears on the inner walls and pillars of mine tunnels. It is formed by the crystallization of water in the mine.