Copper(II) chloride

Copper(II) chloride, also known as cupric chloride, is an inorganic compound with the chemical formula CuCl₂. It comes in two main types: a yellowish-brown anhydrous form and a blue-green form that has water in it, called a dihydrate.

This compound is made in factories for use in an important industrial method called the Wacker process[/w/9].

Both types of copper(II) chloride can also be found naturally as rare minerals. The yellowish-brown form is called tolbachite, and the blue-green form is called eriochalcite.

Structure

Copper(II) chloride has a special shape. In its dry form, it looks like a structure found in cadmium iodide, with copper placed in shapes called octahedrons. Many copper compounds have slightly changed octahedron shapes because of something called the Jahn-Teller effect.

When copper(II) chloride has water added, it still keeps this changed octahedron shape. The copper is surrounded by two water pieces and four chloride pieces.

Copper(II) chloride can attract magnetic fields. It was used in the very first experiments to study this magnetic property by Yevgeny Zavoisky in 1944.

Anhydrous

Dihydrate

Properties and reactions

When you dissolve copper(II) chloride in water, it makes different copper shapes that change color. The color depends on how much you use, the temperature, and if there are other chloride bits around. You might see blue, yellow, or red colors.

If you add a base to copper(II) chloride in water, it makes a blue solid called copper(II) hydroxide. This can also make a special mix called dicopper chloride trihydroxide, which helps keep plants healthy.

Copper(II) chloride can slowly break down when left in air without extra acid. It can also break apart when heated, making copper(I) chloride and chlorine gas. It mixes with certain metals and other substances to make new shapes and compounds.

Preparation

Copper(II) chloride is made by mixing copper with chlorine gas at high heat. This makes copper(II) chloride in liquid form. Another way is to add chlorine gas to a mix of hydrochloric acid and copper, then evaporate the solution to get the form that includes water.

Some copper compounds can react with hydrochloric acid to form copper(II) chloride. This can then be heated to remove the water. The solution can be cleaned by letting crystals form when cooled in a special ice bath. There are other less common ways to create copper(II) chloride using electricity, but these are not usually chosen.

Uses

Copper(II) chloride is used in industry to help change a gas called ethene into a liquid called ethanal. It helps another helper called palladium(II) chloride work better during this change.

Copper(II) chloride is also used to help make other chemicals. It can add chlorine to some compounds and change materials in special ways. It is used to help make chlorine gas, give blue or green color to fireworks, and show changes in humidity on special cards. It is also used in making textiles, cleaning water, and preserving wood.

Natural occurrence

Copper(II) chloride can be found in nature as two rare minerals: tolbachite, which has no water, and eriochalcite, which has water. These minerals are usually found near openings in the earth where hot gases come out and in places where copper is mined. There are also more common minerals made of copper, oxygen, and chlorine, like atacamite, which form in dry areas.

Safety and biological impact

Copper(II) chloride can be harmful if not handled properly. It is important to keep copper ions below 1.3 parts per million in drinking water, as recommended by the US Environmental Protection Agency.

If someone absorbs copper chloride, they might feel a headache, have stomach trouble, experience a drop in blood pressure, and get a fever.

Eating very large amounts can cause serious health problems.

Studies have shown that copper(II) chloride can change the normal behavior of cells in plants, such as onions, and may harm tiny living things in water and soil. It has been found to affect certain bacteria that help clean water, showing that even small amounts can be damaging to the environment.