Friday 10 june 5 10 /06 /Jun 13:51

Warning: Copper(I) chloride is toxic. Do not eat the precipitate or drink the solution. Ammonia vapors are strong. Duck when opening an ammonia bottle as ammonia vapors are lighter than air. Hydrochloric acid can burn skin if splashed on it. Use gloves. Alkalis can burn skin if splashed on it. Use gloves.

 

In an earlier post (http://lanthanumkchemistry.over-blog.com/article-how-to-make-copper-i-chloride-76194624.html), copper(I) chloride was made. I know you probably used it all up, so go ahead and make it again. Keep it in solution this time.

 

Materials necessary:

Containers or test tubes

Sodium hypochlorite (household bleach) for experiment 1

2 copper wires and

12VDC power supply for experiment 2

Household unscented ammonia for experiment 3

Lithium or sodium hydroxide for experiment 4 (how to make alkalis: http://lanthanumkchemistry.over-blog.com/article-how-to-obtain-alkalis-76299009.html)

Hydrochloric acid for experiment 5

 

Copper(I) chloride is a white insoluble compound formed by the reduction of copper(II) chloride with ascorbic acid. In this set of experiments, I will show that:

 

Bleach is an oxidizer.

Copper(I) has a different color than copper(II).

Copper(I) can be reduced further to copper metal.

Copper forms three oxidation states.

Copper(I) forms an ammine complex.

Copper(I) forms an oxide with bases.

Copper(I) forms a chloride complex.

 

First: Take some copper(I) chloride solution and add sodium hypochlorite. It will oxidize the white copper(I) chloride to green copper(II) hydroxide.

Second: Place the two copper wires in a copper(I) chloride solution. Attach them to your power supply. Turn it on. There should be red copper metal forming at the negative electrode, along with hydrogen. There is still the white copper(I) in the middle. You may see copper(II) forming at the anode as the copper wire is oxidized. Here are all the three oxidation states of copper.

Third: Add ammonia to copper(I) chloride solution. It clears up. After a while, it starts turning blue on the surface. This is the oxidation of the colorless copper(I) ammine complex to the bright blue copper(II) ammine complex by the oxygen in tha air.

Fourth: Add your alkali solution to the copper(I) chloride solution. A bright yellow to orange precipitate is formed. This is microparticulate copper(I) oxide. It will oxidize in air just like copper(I) chloride. In a later experiment, the red copper(I) oxide will be formed.

Fifth: Add hydrochloric acid to the copper(I) chloride solution. It will dissolve. This is a copper(I) complex with chloride ions.

 

In this experiment, you have seen oxidation by oxidizing agent, oxidization and reduction by electrolysis, formation of an ammine complex and oxidation of that ammine complex, formation of an oxide by reaction with a base, and a water-soluble chloride complex.

 

This picture is the microcrystalline copper(I) oxide formed by reaction of copper(I) chloride with alkali:

 

Cuprous-oxide-microcrystalline-2.JPG

 

By LanthanumK - Posted in: Experiments
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