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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]
The CuTi 2 structure of the lanthanum, cerium and praseodymium diiodides along with HP-NdI 2 contain 4 4 nets of metal and iodine atoms with short metal-metal bonds (393-386 La-Pr). [10] these compounds should be considered to be two-dimensional metals (two-dimensional in the same way that graphite is). The salt-like dihalides include those of ...
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.
The term derives from lanthanum, first discovered in 1838, at that time a so-called new rare-earth element "lying hidden" or "escaping notice" in a cerium mineral, [12] and it is an irony that lanthanum was later identified as the first in an entire series of chemically similar elements and gave its name to the whole series.
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
For overall selectivity the same problem of the conflicting definitions exists. Generally, it is defined as the number of moles of desired product per the number of moles of undesired product (Definition 1 [3]). However, the definitions of the total amount of reactant to form a product per total amount of reactant consumed is used (Definition 2 ...
When one mole of water is added to a large volume of water at 25 °C, the volume increases by 18 cm 3. The molar volume of pure water would thus be reported as 18 cm 3 mol −1. However, addition of one mole of water to a large volume of pure ethanol results in an increase in volume of only 14 cm 3. The reason that the increase is different is ...
Lanthanum diiodide can be obtained from the reduction of lanthanum(III) iodide with lanthanum metal under a vacuum at 800 to 900 °C: [3] La + 2 LaI 3 → LaI 2. It can also be obtained by reacting lanthanum and mercury(II) iodide: [3] La + HgI 2 → LaI 2 + Hg. It was first created by John D. Corbett in 1961. [4]