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A lanthanum hexaboride hot cathode. Lanthanum hexaboride cathodes. Lanthanum hexaboride powdered. Lanthanum hexaboride (La B 6, also called lanthanum boride and LaB) is an inorganic chemical, a boride of lanthanum. It is a refractory ceramic material that has a melting point of 2210 °C, and is insoluble in water and hydrochloric acid. [1]
Assuming the unknown compound behaves as an ideal gas, the number of moles of the unknown compound, n, can be determined by using the ideal gas law, = where the pressure, p, is the atmospheric pressure, V is the measured volume of the vessel, T is the absolute temperature of the hot bath, and R is the gas constant.
The SI value of the mole was chosen on the basis of the historical definition of the mole as the amount of substance that corresponds to the number of atoms in 12 grams of 12 C, [1] which made the mass of a mole of a compound expressed in grams, numerically equal to the average molecular mass or formula mass of the compound expressed in daltons.
Cerium hexaboride (Ce B 6, also called cerium boride, CeBix, CEBIX, and (incorrectly) CeB) is an inorganic chemical, a boride of cerium. It is a refractory ceramic material. It has a low work function, one of the highest electron emissivities known, and is stable in vacuum. The principal use of cerium hexaboride is a coating of hot cathodes. It ...
EuFOD, an example of a europium complex. It has been known since the early 1930s that the salts of certain lanthanides are fluorescent. [4] The reaction of lanthanide salts with nucleic acids was discussed in a number of publications during the 1930s and the 1940s where lanthanum-containing reagents were employed for the fixation of nucleic acid structures. [3]
The mean oxidation number for the boron atoms is then simply the ratio of hydrogen to boron in the molecule. For example, in diborane B 2 H 6, the boron oxidation state is +3, but in decaborane B 10 H 14, it is 7 / 5 or +1.4. In these compounds the oxidation state of boron is often not a whole number.
Lanthanum nitride can be prepared from the reaction of nitrogen and lanthanum trihydride: 2LaH 3 + N 2 → 2LaN + 3H 2. It can also be prepared from the reaction of ammonia and lanthanum trihydride: [3] LaH 3 + NH 3 → LaN + 3H 2. The reaction of nitrogen and lanthanum amalgam can also work: [4] 2La + N 2 → 2LaN
Lanthanum is a chemical element with the symbol La and the atomic number 57. It is a soft , ductile , silvery-white metal that tarnishes slowly when exposed to air. It is the eponym of the lanthanide series, a group of 15 similar elements between lanthanum and lutetium in the periodic table , of which lanthanum is the first and the prototype.