Copper Sulphate to Make Bordeaux Mixture


Copper sulphate is one of the most important copper sal […]

Copper sulphate is one of the most important copper salts and is widely used in electroplating, printing and dyeing, pigments and pesticides. The inorganic pesticide Bordeaux mixture is a mixture of copper sulfate and lime milk. It is a good fungicide and can be used to control diseases of various crops. In 1878, in the city of Bordeaux, France, most of the vines died of worm disease, and the trees on both sides of the road were afraid of pedestrians picking. The trunk was coated with quicklime and copper sulphate solution, the trunk was whitened, and the pedestrians looked uncomfortable. Eat, these trees are not dead, further research knows that this mixture has bactericidal ability, hence the name Bordeaux mixture.

Copper sulphate is used to prepare Bordeaux mixture. The ratio of copper sulphate and quicklime (preferably bulk fresh lime) is generally 1:1 or 1:2. The amount of water is also determined by factors such as different crops, no disease and seasonal temperature. It is best to use the "two-liquid method" when preparing, that is, firstly mix the copper sulfate and the quick lime with the required half amount of water, and then pour into another container at the same time, and continuously stir to obtain a navy blue gel. Bordeaux mixture should be used now, because the gelatinous particles will gradually become larger and lower and the effect will be reduced. Copper sulfate is also commonly used to prepare other copper compounds and electrolytes for electrolytically refining copper. Copper sulfate pentahydrate can be obtained by copper or copper oxide and sulfuric acid, and concentrated and crystallized. In the laboratory, concentrated copper sulfate can be used to oxidize metallic copper to prepare anhydrous copper sulfate.

Copper sulfate reacts only with a small amount of water. If there is a large amount of water, copper sulfate will dissolve in water to form a copper sulfate solution. The formed copper sulfate solution is evaporated to reduce the water to a certain extent, and the copper sulfate undergoes the above chemical reaction with water. The copper sulfate solution is concentrated and crystallized to obtain a blue crystal of copper sulfate pentahydrate, commonly known as cholesteric, copper or blue enamel, and has a relative density of 2.284. The cholestasis is stable under normal temperature and normal pressure, does not deliquesce, and gradually weathers 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. Anhydrate. Anhydrate is also easily converted to cholesta.