Platinum nanoparticles of diameter ∼2 nm are important catalysts in carbon monoxide oxidation to carbon dioxide. Platinum crystallizes in a face-centered cubic arrangement with an edge length of 3.924 Å. Estimate how many platinum atoms are on the surface of a 2.0-nm Pt sphere, using the surface area of a sphere 14pr22 and assuming that the “footprint” of one Pt atom can be estimated from its atomic diameter of 2.8 A ° .

Identify each of the following equations as which types of chemical reaction ?Cl2 +NaI ------ NaCl + I2 A. Combination B. Decomposition C. Single displacement

Kristen Mcku The Packing of Atoms and Ions in Crystals Note: Please put all the answers in decimal form. Assume the radius of each sphere = 1.00 A. 1. A Study of Metallic Crystals a. Body-Centered Cubic Why is this structure called body-centered cubic? Because the one carbon atom is the center of the cube. What is the coordination number of a sodium atom when packed in a crystal of this type? If this model were extended in all directions, what difference, if any, would there be in the relative position of corner sphere and those in the center? Note: In the calculations below, consider all distances to be measured between the centers of the spheres. From a study of the right triangles involved in a cube, as illustrated below, where (a) is the edge length. (f) is the face diagonal, and (b) is the body diagonal, the following is apparent: a 711 b b² = f² + a² f = a² + a² b² = 3a² In calculating the volumes, not that only one-eighth of each of the corner spheres is inside the cube which…

In the early days of X-ray crystallography there was an urgent need to know the wavelengths of X-rays. One technique was to measure the diffraction angle from a mechanically ruled grating. Another method was to estimate the separation of lattice planes from the measured density of a crystal. The mass density of NaCl is 2.17 g cm−3 and the (100) reflection using radiation of a certain wavelength occurred at 6.0°. Calculate the wavelength of the X-rays.

The density of platinum is 21.45 g/cm3.  It crystallizes in a fcc lattice. Calculate its metallic radius.