Molar mass lithium

Suppose that Si-28 ( Si) is taken as the standard for expressing atomic masses and assigned an atomic mass of 10.00 amu. Estimate the molar mass of lithium nitride. 

E.7 The nuclear power industry extracts 6Li but not Li from natural samples of lithium. As a result, the molar mass of commercial samples of lithium is increasing. The current abundances of the two isotopes are 7.42% and 92.58%, respectively, and the masses of their atoms are 9.988 X 10-24 g and 1.165 X 10 21 g, respectively, (a) What is the current molar mass of a natural sample of lithium (b) What will the molar mass be when the abundance of 6Li is reduced to 5.67% ... 

Lithium metal had few uses until after World War II, when thermonuclear weapons were developed (see Section 17.11). This application has had an effect on the molar mass of lithium. Because only lithium-6 could be used in these weapons, the proportion of lithium-7 and, as a result, the molar mass of commercially available lithium has increased. A growing application of lithium is in the rechargeable lithium-ion battery. Because lithium has the most negative standard potential of all the elements, it can produce a high potential when used in a galvanic cell. Furthermore, because lithium has such a low density, lithium-ion batteries are light. 

Our task is to estimate the volume occupied by one atom of lithium. As usual, the mole is a convenient place to begin the calculations. Visualize a piece of lithium containing one mole of atoms. The molar mass, taken from the periodic table, tells us the number of grams of Li in one mole. The density equation can be used to convert from mass to volume. Once we have the volume of one mole of lithium, we divide by the number of atoms per mole to find the volume of a single atom. 

Naphthalene lithium (0.5 mmol) in THE is added quickly to a cooled (-78 °C) solution of styrene (5 g) in THE (50 ml).The mixture immediately turns orange. Stirring at -78 °C is continued for 30 min. A small sample may be taken from the mixture with a syringe and quenched in degassed methanol.This sample can be used to measure the molar mass of the styrene block (by GPC).The mixture is allowed to warm to -18 °C, then a solution of 1,1-diphenylethylene (108 mg, 0.6 mmol) in THE (1 ml) is added whereupon the... 

Example Problem Calculate the average thermal neutron capture cross section and the mean free path for LiF, a solid crystalline material at room temperature with a density of 2.635 g/cm3 and a molar mass of 25.94 g/mol. Lithium has two stable isotopes 6Li (7.5%) and 7Li (92.5%) with thermal neutron capture cross sections of ct thermal = 39 mb and 45 mb, respectively. Fluorine is monoisotopic, 19F, with (Tthermal = 9.6 mb. 

The units are correct. Lithium hydroxide has a molar mass that is about half of carbon dioxide s molar mass, but there are twice as many moles of lithium hydroxide. Therefore it makes sense that the mass of lithium hydroxide required is about the same as the mass of carbon dioxide produced. 

Step 4 Use the periodic table to determine the molar mass of lithium carbonate. To find the mass of lithium carbonate produced, multiply the number of moles by the molar mass. 

Fig. 2 shows MALDI-MS spectra of the same three samples.The spectra usually show the mole peaks plus the molar mass of Na (23 Da) and K (39 Da). Unless they have been specifically added, the sodium and potassium ions come fi-om contaminants in the specimen and/or the matrix. Alternatively, another suitable salt may be added. The addition of lithium chloride suppresses sodium (and potassium) ions, so that the spectra can be more easily interpreted. Thus, the numbers in Fig. 2a refer to mole peaks M plus a (= M + 23 Da) and in Fig. 2b and 2c to M plus Li (= M + 7 Da). As can be seen, the resolution in the higher molecular mass range is more pronounced than in SFC. Components with more than 100 monomer units can be separated in the diol sample. 

Prepare a spreadsheet similar to the one shown in Figure 3-7 for the gravimetric determination of nickel using dimethylglyoxime. See Section 37B-3 for details. Use the worksheet from Problem 3-9 to calculate the molar mass of Ni(DMG)2 if it is available. 3-4. Write an Excel formula using the FIND and MID functions to eliminate the square brackets and the uncertainty from the atomic mass of lithium in the lUPAC table and display the numeric characters of the atomic weight. 

Step 2 To determine the limiting reactant, we must convert the masses of lithium (atomic mass = 6.941 g) and nitrogen (molar mass = 28.02 g) to moles. 

Since the early days of ferroelectric low molar mass LC research, the exploration of the NLO properties of these substances has been a topic of interest. For a recent review on SHG in ferroelectric LCs, see [215]. Unfortunately, the SHG efficiency of most ferroelectric LCs investigated so far [216-219] is orders of magnitude below that of state-of-the-art inorganic crystals, such as lithium niobate. The main reason for the low electronic NLO activity is that the ferroelectric LC compounds and mixtures used in these investigations were optimized for display applications rather than for NLO performance. Quite recently, some research groups started the development of ferroelectric LC compounds specifically devoted to NLO applications, and indeed improved the SHG efficiency by orders of magnitude [220-224]. 

We need the molar masses of lithium hydroxide and carbon dioxide. How Do We Get There ... 

The m-dilithium compound, LiCBioHioCLi, is obtained by reaction of m-carborane with butyl lithium. After a subsequent polycondensation with water, and acid-catalyzed reaction of this compound with dichlorodisiloxane gives polymers with a molar mass of " 15 000-30 000 ... 

Polystyrene-b-poly(vinylpyridine) with a molar mass of lOOOOgmol" was synthesized by the lithium naphthalide-initiated sequential polymerization of styrene and 2-vinylpyridine, followed by end-to-end intramolecular coupling with l,4-bis(bromomethylbenzene) in THF. The block copolymer was finally purified by predpitation-extraction procedures. 

The advantage of the battery is that lithium has the most negative standard reduction potential valne (see Table 13.1). Furthermore, lithium is the lightest metal, so that only 6.941 g of Li (its molar mass) is needed to produce 1 mole of electrons. A lithium-ion battery can be recharged literally hundreds of times without deterioration. These desirable characteristics make it suitable for use in cellular telephones, digital cameras, and laptop computers. 

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