Rubidium

Rubidium is an alkali metal with the chemical symbol Rb and an atomic number of 37. It is a rare element due to its even distribution through the Earth's crust and not having any known ores with a concentration higher than 1%. The world production of rubidium compounds is between 2-4 tonnes per year.

Properties

Chemical

Rubidium will react quickly and violently with water producing rubidium hydroxide and hydrogen. It will also reaction with halogens to form the corresponding halides.

Physical

Rubidium is a soft, silvery metal which will tarnish quickly in air. It can melt on a hot day.

Availability

Rubidium metal is very highly reactive and shipping regulations are very strict. It is offered by element dealers such as Metallium at very high prices(~$150/g). Rubidium salts are available to the public on sites like eBay, but they are still priced at around $3/g.

Preparation

Rubidium metal can be prepared by dry distillation of a rubidium halide and lithium metal, yielding the lower boiling rubidium coming off as a gas and being condensed in a glass vessel. This is extremely dangerous and the risk of explosion is very high. It must be done in a fully argon atmosphere and the reaction takes place at high temperatures.

Projects

• Make rubidium hydroxide
• Rubidium suboxides
• Colored flash powders with rubidium salts

Handling

Safety

Rubidium metal is extremely dangerous as it will catch fire in moist air and explode on contact with water. In long term storage in mineral oil, it will also react with air to form shock sensitive explosive peroxides, similar to potassium. In its ionic form, rubidium ions are extremely similar to potassium ions, and replace throughout the body. However, due to their similarity, this caused no ill effects in study participants with 100x the normal amount (0.36g) of rubidium in a human. Mice were able to survive with significant fractions of potassium in their bodies replaced with rubidium, but when the rubidium:potassium ratio approached 1:1 the mice died.

Storage

Rubidium can be stored in mineral oil, but since rubidium is much more reactive than sodium or potassium, it will oxidize much faster. It's best stored under inert atmosphere, such as argon.

Disposal

As rubidium is pricey, it's best to try to recycle it.