Concise Physical Chemistry

c11 JWBS043-Rogers September 13, 2010 11:26 Printer Name: Yet to Come

180 LIQUIDS AND SOLIDS

CRC Handbook of Chemistry and Physics, 2008–2009, 89th ed. The unit is millinew-

tons per meter; be careful not to confuse the two meanings for the letter m. What is

the capillary rise of water in a tube 1.000 mm in diameter?

Problem 11.3

The strongest (first-order) reflection of X rays comes when a crystal under exami-

nation is at an angle of 37. 5 ◦to the incident beam of radiation. The wavelength of

the X-radiation isλ= 1. 54 A ̊=154 pm. What is the distance between the reflecting

planes?

Problem 11.4

Suppose that discs of radiusr=1 unit are arranged on a table top in the patterns

in Fig. 11.14 as they are in Figs. 11.7 (left) and 11.8 (right). Find the unit cell and

packing fraction for these arrangements.

FIGURE 11.14 Close packing (left) and simple square unit cells (right).

Problem 11.5

The coordination number of an atom in a unit cell is the number of nearest neighbors.

Because the entire crystal is constructed of replicated unit cells, all atoms in the

system have the same coordination number. What is the coordination number of the

body-centered cubic unit cell in Fig. 11.15?

FIGURE 11.15 A body-centered primitive cubic cell.