Simple metal hydrides contain hydrogen in their crystal structure. These simple metal hydrides include binary and intermetallic hydrides. Binary hydrides contain only one metal and generally represented as MHx, were M stands for metal. The intermetallic hydrides contain at least two metals in addition to the hydrogen and generally represented by the formula AmBnHx, where A, B are metals. These are further classified in to AB (CsCl structure), AB2 (Laves phase), A2B (AlB2 structure type), AB5 (CuC5 structure type). In these hydrides, metal A has strong affinity for hydrogen and B does not interact with hydrogen.
The binary metal hydride containing high gravimetric storage capacity is alane (AlH3) with 10.1 wt%. Another important simple metal hydride is MgH2. Binary metal hydrides generally have low storage capacity. Among the intermetallic compounds, LaNi5H6 is widely used and commercially available
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These complex metal hydrides have high gravimetric storage capacity than the simple metal hydrides. Nitrogen containing hydrides such as amines or imides, and boron containing hydrides (borohydrides) are the main categories in complex metal hydrides. Lithium imide (Li2NH), magnesium amide (Mg(NH2)2), lithium borohydride (LiBH4) and sodium borohydride (NaBH4) are the actively explored complex metal hydrides for the hydrogen storage applications. Li2NH reversibly store 6.5 wt% of hydrogen however the required temperature to burn the fuel is high and cannot be used in onboard vehicles. In addition, amides and imides produce ammonia as the effluent. The LiBH4 and NaBH4 have a very high gravimetric storage capacity of up to 18 wt%. However, desorption temperature of 673 K is required to remove the hydrogen atoms. Thus these complex metal hydrides are not promising materials for hydrogen storage (Satyapal et al (2007 & Durbin & Malardier-Jugroot
The ratios for NaBH4, MPV, and L-selectride are 24.2:75.8, 43.6:56.3, 91.3:.86 respectively. According to analysis of the 1H-NMR spectrum, it is shown that the trans product formed over the cis. The mechanism for L-selectride is very similar to that of NaBH4, but NaBH4 primarily yields the more trans isomer whereas the L-selectride primarily the cis isomer. The reason for this is because in NaBH4, the hydride is not being blocked when convert to OH so it’s free to do a top attack to make a lot more of the the trans isomer. Whereas the L-selectride has bulky groups that block from the carbonyl oxygen which means that it must perform bottom attack and because of this, the isomer that gets made is the cis at 91%. In MPV, the proton is free to attack the carbonyl oxygen in a frontside attack to give more of the trans isomer The MPV reaction using aluminum isopropoxide gives reversible reduction of ketones and aldehydes and the cis or trans can revert back to starting ketone. Each step in the mechanism is reversible so the reaction is driven by the formation of the more stable product which favored thermodynamic. Overall, the stereoselectivity of reaction is affected how the hydride is opened was when it was attacking the carbonyl
The “tetrahydido” in the names mean that there are four hydrogens around the aluminium or boron in the negative ion. The structures for both reducing agents contain negative ions and there are empty orbitals on the aluminium or boron due to the co-co ordinate covalent bonds which use lone pairs of electrons from the hydride ion. The same principles would go to the reduction of aldehydes and ketones where you get the same organic compound. It does not matter whichever reducing agent is used. In the reaction of nucleophilic addition, the aldehyde and the ketone act the same way.
Molybdenum is a transition metal. It is represented by the symbol Mo. It is a pure metal that is is silverish white in color and very hard, and has one of the highest melting points of all pure elements at 4753 °F. Its boiling point is 8382 °F. Its density is 10280 kg/m3 and its hardness is 5.5.
Beryllium has the symbol Be. In the older chemical literature, beryllium is called glucinium after the Greek word glykys meaning sweet, because of Vauquelin's initial description and observation of Beryllium. Beryllium's atomic number is 4, its atomic weight is 9.01 and in its pure metal form it melts at 1278 degrees Celsius.
...itrogen? Than Bromine? Why Is Hydrogen so Weird? :. N.p., n.d. Web. 16 Jan. 2014.
of a zwitterion is made possible due to the basic properties of the NH2 group
Zn (zinc) these metals will react with hydrochloric acid as they. Fe (iron) is higher in the reactivity series than hydrogen. Sn (tin) and so a displacement reaction will take place. Pb (lead) . H (hydrogen) - a. Cu (copper)
In the face of a potential H2N2 epidemic, New Jersey’s Health Commissioner enforced a statute requiring the vaccination of all public health professionals, school-age children, pregnant mothers, and asthmatics. The law also prohibits people outside these high-risk groups from receiving inoculations voluntarily until these classes of people are fully vaccinated. The states, as governments of general jurisdiction, have police powers to pass legislation designed to protect society’s health and safety. As such, New Jersey needs no specifically enumerated constitutional power to enact such legislation. Indeed, the Supreme Court in Jacobson v. Massachusetts upheld a state law requiring mandatory immunization even in the face of concerns about vaccine safety and bodily integrity.
Femicide is defined as the act of killing a female simply because she is female. Acts of femicide includes “honor killings,” “dowry deaths,” genital mutilation, rape in war and victimization o female refugees. The treatment of women prisoners and detained immigrant women are also related to the issue of femicide. Essentially, femicide is a form of gender-based violence (Stuart van Wormer & Bartollas, 2011). It is considered to be an extreme form of gender-based violence that may include torture, mutilation, cruelty and sexual violence. The violence often culminated to murder. This violence is linked to gender concepts like inequality, discrimination and disempowerment (Femicide, 2008). It is also viewed as “a form of terrorism that functions to define gender lines, enact and bolster male dominance, and to render women chronically and profoundly unsafe” (Suarez, 2009). Based on international federal and state law, women have the right to be free from violence. Overall, acts of femecide are viewed as a violation of the human rights of women (Femicide, 2008).
The methane reformer is a chemical synthesis that turns methane into pure hydrogen, using a catalyst. The hydrogen produced can be applied in numerous areas, such as, hydrogenation of fats and oil, production of ammonia and also in fuel cells (a device that produces electricity by combining hydrogen and oxygen). Platinum is usually used as a catalyst in the methane reformer and plays a vital role in fuel cells. Platinum is a very effective metal because it has the right amount of strength in absorbing: enough so it holds and activates the reactants and not too strong so that the products can’t break away. However, Vincent Artero, a research scientist at Commissariat à l’Énergie Atomique, says, “The problem with platinum is that it’s a very
Iron comes from the Latin word ferrum. From ferrum its symbol became Fe. The atomic number of iron is 26, and its atomic weight is 55.845. Iron is a magnetic, bendable, shiny white metallic element.
I am going to discuss about the element known as gold in my assignment. To describe the element gold in simple terms, I can only say that it is an element (chemical element). This element is denoted by the symbol Au. It has an atomic number of seventy nine (79). I will describe quite a number of things concerning gold as an element. To begin with is:
Aluminum is one of a number of soft metals that scientists call "poor" metals. It can be shaped and twisted into any form. It can be rolled into thick plates for armored tanks or into thin foil for chewing gum wrappers. It may be drawn into a wire or made into cans. Aluminum is a generally popular metal because it does not rust and it resists wear from weather and chemicals. (Bowman, 391) Aluminum is an element. Its atomic number is thirteen and its atomic weight is usually twenty-seven. Pure aluminum melts at 660.2ºC and boils at 2500ºC. Its density is 2.7 grams per cube centimeter. Aluminum is never found uncombined in nature. (Bowman, 391) Aluminum is a very useful metal that is light, easy to shape and can be strong. This makes aluminum one of the most used metals in the world, right behind iron and steel. (Geary, 185) In its pure state, aluminum is quite weak compared to the other metals. However, its strength can be greatly increased by adding small amounts of alloying elements, heat-treating, or cold working. Only a small percentage of aluminum is used in its pure form. It is made into such items as electrical conductors, jewelry, and decorative trim for alliances and cars. A combination of the three techniques has produced aluminum alloys that, pound for pound, are stronger than structural steel. Some common metals used in alloys for aluminum are copper, magnesium and zinc.(Walker, 31) The added elements give the aluminum strength and other properties. (Newmark, 41) Aluminum is one of the lightest metals. It weighs about 168.5 pounds per cubic foot, about a third as much as steel which weighs 487 pounds per cubic foot. (Neely, 214) As a result, aluminum has replaced steel for many uses. For example, some ...
In chemistry, metals compose a great number of the periodic table elements. Each metal has its own characteristic mass,