Platinum

Platinum is a chemical element with the chemical symbol Pt and the atomic number 78. It is a valuable and useful transition metal, part of the so called "platinum group metals".

Properties

Chemical

Platinum is extremely resistant to organic and mineral acids. It will, however, dissolve extremely slowly in hot aqua regia, to give chloroplatinic acid.

Pt + 4 HNO₃ + 6 HCl → H₂PtCl₆ + 4 NO₂ + 4 H₂O

It will also be attacked by molten alkali and cyanides.

Physical

Platinum is a lustrous, ductile, and malleable, silver-white metal. It is more ductile than gold, but less malleable.

Availability

Although it can be bought from precious metal stores, platinum is also found in certain electronics and car exhaust catalysts. Electrodes are sometimes coated with platinum. Platinum can be obtained along with silver in small amounts from capacitors obtained through electronic recycling.

Platinum bullion can be bought, which has the advantage of having purity expressed accurately.

Preparation

Platinum can be extracted by dissolving it in aqua regia. The resulting chloroplatinic acid is converted to ammonium chloroplatinate by the addition of ammonium chloride, that can be reduced to platinum metal by heating it, usually in a hydrogen atmosphere. This results in a platinum sponge.

Projects

• Make hexachloroplatinic acid
• Make platinum electrodes
• Electrolysis
• Make chlorates and perchlorates

Handling

Safety

Being a noble metal, it is non-toxic, though some of its compounds should be handled with care.

Storage

No special storage is required for storing platinum, though platinum electrodes should be kept away from sulfur oxides which can "poison" it.

Disposal

It's best to recycle platinum, considering it's a rare and expensive metal.

References

Relevant Sciencemadness threads

• Making Platinum Electrodes