UPt3 is a metallic compound and is classified as a heavy fermion. (Electrons are
ID: 887502 • Letter: U
Question
UPt3 is a metallic compound and is classified as a heavy fermion. (Electrons are called fern and the "heaviness" comes from the strong interactions between the conduction electrons ana m surrounding atoms.) UPt3 exhibits a superconducting transition at 0.35 K, and for years was considered to be a typical superconductor with properties similar to all previously discovered superconductors. In 1988, a sample of UPt3 was prepared at Los Alamos National Laboratory by carefully weighing stoichiometric quantities of depleted U and Pt. This same sample was measured at Berkeley and found to be the first unconventional superconductor; that is, the first superconductor to display properties radically different from all other superconductors. The difference in this sample and previous samples of UPt3 was simply the stoichiometric mixture. The physicist at Los Alamos took the time to carefully compute the correct mass of each starting material. You have a large supply of depleted U (highly controlled) and Pt (highly expensive), and you wish to make 5.0000 g of UPt3. You have access to a laboratory balance that has a resolution of 0.1 mg and the necessary safety equipment. What mass of depleted U and Pt must be weighed out and then melted together to form pure UPt3 (no excess U or Pt)? Depleted U has had the 2351 removed for industrial or military purposes leaving an isotopic mixture that, for all practical purposes, is all 238U. The atomic mass of 235U is 235.0439, and that of 238U is 238.0508. The atomic mass of naturally occurring U is 238.02891.Explanation / Answer
Molar mass of Pt= 195.084 gm
Since you want to use U 23,molar mass of U = 235.0439gm
Molar mass of UPt3 = 235.0439 + 3* 195.084 = 820.2959 gm
Mass of UPt3 = 5.0 gm
Number of moles of UPt3 = mass / molar mass
=5/ ( 820.2959 )
=6.0954*10^-3 mol
mol of U required = 6.0954*10^-3 mol
Mol of Pt required = 3*6.0954*10^-3 mol = 1.8286*10^-2 mol
Mass of U required = 6.0954*10^-3 * 235.0439 = 1.4327 g = 1432.7 mg
Mass of Pt required = 1.8286*10^-2 * 195.084 =3.5673 g = 3567.3 mg
they should melted
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