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Rubidium Element scroll down to download  Rubidium was discovered by the German chemists Robert Bunsen and Gustav Kirchhoff in 1861 while analyzing samples of the mineral lepidolite (KLi 2 Al(Al, Si) 3 O 10 (F, OH) 2 ) with a device called a spectroscope. The sample produced a set of deep red spectral lines they had never seen before. Bunsen was eventually able to isolate samples of rubidium metal. Today, most rubidium is obtained as a byproduct of refining lithium. Rubidium is used in vacuum tubes as a getter, a material that combines with and removes trace gases from vacuum tubes. It is also used in the manufacture of photocells and in special glasses. Since it is easily ionized, it might be used as a propellant in ion engines on spacecraft. Recent discoveries of large deposits of rubidium suggest that its usefulness will increase as its properties become better understood. Rubidium forms a large number of compounds, although none of them has any significant commer...

chlorine Gas Scroll down to download Gaseous chlorine is poisonous and classified as a pulmonary irritant. It has intermediate water solubility with the capability of causing acute damage to the upper and lower respiratory tract. Chlorine gas has many industrial uses, but it was also once used as a chemical weapon in World War I. Today, most incidents of chlorine exposure are through accidental industrial or household exposures. As for industrial exposures, there have been several instances of train accidents carrying liquid chlorine that caused the release of chlorine gas to the surrounding environment. At home, a mixture of chlorine bleach with other household products that contain acid or ammonia is a common source of exposure to chlorine gas. Toxicity to chlorine gas depends on the dose and duration of exposure.  At concentrations of 1 to 3 ppm chlorine gas acts as an eye and oral mucous membrane irritant, at 15 ppm there is an onset of pulmonary symptoms, and it c...

TiO 2  and ZrO 2  in biomass conversion Scroll Down To Download Biomass refers to plant-based materials that are not used for food or feed. As an energy source, lignocellulosic biomass (lignin, cellulose and hemicellulose) can be converted into various forms of biofuel using thermal, chemical and biochemical methods. Chemical conversion implies the use of solid catalysts, usually oxide materials. In this context, reducible oxides are considered to be more active than non-reducible oxides. But why? Using density functional theory DFT + U calculations with the inclusion of dispersion forces, we describe the properties of anatase TiO 2 , a reducible oxide, and tetragonal ZrO 2 , a non-reducible oxide, the (101) surfaces in this context. In particular, we focus on the role of surface reduction, either by direct creation of oxygen vacancies via O 2  desorption, or by treatment in hydrogen. We show that the presence of reduced centres on the surface of titania or zircon...