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Finding treasures is a challenge and usually useless. And yet, we offer you to try your luck, ensuring complete success. We will be looking for real gold, and not in a cave and not in the forest, and on the plate with a gold platter. And not even for the whole, and broken.

Maybe you will be surprised, but the gold rim on the dishes is really made of gold. However, it there is very little, because the layer is very thin. Take a glass with a gold rim and look to the light: a layer of gold seems to be transparent.

Gold utensils is applied from a solution. And we begin this experience with preparation of a solution containing gold.

Stock up on shards with gold you get for free in a China shop. For experiments that you only have about 10 cm2 gold. From it we will make about 5 ml of the diluted zolotoporfirovoe acid H[AuCl4]. To do this, dissolve the gold in the mixture of concentrated acids - 3 ml of saline and 1 ml of nitric. This mixture is called Imperial vodka. Contact with concentrated acids should very carefully! Wear rubber gloves! To put the experience in the chemical mug!

Before the dissolution of the wash layer of gilding on the bat, bowl and remove the sebum, wiping it with a cotton swab dipped in acetone. In a glass pipette type a few drops of Aqua Regia and dissolve the gold. The resulting solution zolotoporfirovoe acid gently gather in a small test tube, dug distilled water. All solutions in this experience should also be prepared in distilled water and clean the dishes.

In order to make fuller use of gold, where it is dissolved, rinse with a small amount of water (preferably from a pipette) and assemble it in the same tube. Top up with water to 5 ml of this solution and will work. We will prepare a very beautiful kassaby purple - colloidal solution containing fine particles of metallic gold. It is formed when highly diluted solution zolotoporfirovoe acid add a solution of tin chloride SnCl2.

Dissolve 0.5 g of tin chloride (II) in 50 ml of water. A few drops of this clear solution pour into a test tube with a pale yellow solution zolotoporfirovoe acid. At first the mixture will turn yellow-brown, and in a few minutes will have a wonderful coloring kassabova purpura. When the metallic gold is recovered, and the resulting tin hydroxide Sn(OH)4 gives a colloidal solution stability. The color of the liquid is usually intensely red, but depending on the size of the particles can have various shades from pink to purple.

Colloidal gold can be precipitated with a solution of salt. Gold particles in this together and drown. After washing and drying of the precipitate can be obtained (using Aqua Regia) solution zolotoporfirovoe acid.

If you have a hydrogen burner, you can put a very impressive experience, the so - called experience Donau. The flame of hydrogen is directed to the surface of the solution zolotoporfirovoe acid, also recovers gold and fluids appear colored strips. You can do it: apply to clean porcelain plate undiluted solution of the acid obtained in the processing of gold Imperial vodka, dry it, and then placed in a hydrogen flame burner. Porcelain forms a shiny film of gold.

Caution: hydrogen burner can be used only with the permission and in the presence of the teacher.

O. Holguín. "Experiments without explosions"
M., "Chemistry", 1986


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